SBA Chest

Findings: Chest x-ray shows a left-sided pneumothorax and diffuse irregular nodular opacities.

D. Correct. The descending aortic interface is formed by the juxtaposition of the aerated lung and the opacity of the left lateral margin of the descending thoracic aorta. The interface is visible from the top of the aortic arch to the level of the diaphragm inferiorly. Since the descending thoracic aorta is a posterior structure, abnormalities that obliterate the descending aortic interface are within the posterior mediastinum. Of the choices provided, only neurogenic tumors occur in the posterior mediastinum. Thus, they are most likely to obliterate the descending aortic interface.

B. Correct. This radiograph represents the classic findings of right upper lobe collapse with increased opacity and volume loss. The central mass results in a convex inferior border which simulates a backwards “S” when viewed adjacent to the upper portion of collapse. This “Reverse S of Golden” should trigger the reader to think of a mass when it is present, usually bronchogenic carcinoma.

A. Incorrect.
B. Webs are seen with chronic emboli and represent residual thrombus or scarring in a recanalized vessel. Occasionally, these may calcify. They are much easier to see on angiography or coronal reconstructions of pulmonary embolism protocol CT.
C. Correct. The railroad track sign or doughnut sign (with the clot centrally and contrast peripherally) is a direct sign of acute pulmonary embolus on CT. Chronic pulmonary embolus tends to be eccentric. Occasionally, acute pulmonary embolus may be eccentric. The margin with the lumen, in these cases, tends to be convex as compared to chronic pulmonary embolus which has a flat or concave margin to the lumen.
D. Mosaic attenuation or perfusion is a finding more commonly seen with chronic emboli. The vessels in the darker regions are attenuated and the darker regions do not demonstrate air-trapping.

D. Correct. The left superior vena cava (SVC) drains into the right atrium via the coronary sinus. A leftsided SVC, a normal anatomic variant, is found in 0.3% of normal individuals. 80% of such individuals also have a right-sided SVC and 60% have a left BCV connecting to the right and left SVCs.

A. Bilateral hilar and right paratracheal adenopathy is common. Anterior mediastinal adenopathy/mass usually signifies lymphoma or thymoma.
B. The disease in sarcoidosis tends to be predominantly upper lobe in distribution.

D. Correct. Pulmonary venoocclusive disorder is a rare disorder characterized by obliteration of small pulmonary veins. This leads to pulmonary hypertension. The causes are many and include viral infections, inhaled toxins and immune complex deposition within the lung to name a few. Diagnosis is suggested in a patient with pulmonary hypertension when radiographic features demonstrate enlarged pulmonary arteries, diffuse interstitial edema and small to normal sized left atrium.

C. Correct. Small cell carcinoma is a form of lung cancer. It accounts for 15 – 20% of all lung cancers. It is characterized by rapid growth, early metastasis and extremely poor prognosis. It is associated with paraneoplastic syndromes, including Cushing’s syndrome and inappropriate ADH secretion. Inappropriate ADH secretion results in hyponatremia. Hypoglycemia, brachial plexopathy and pupillary constriction are not clinical features of small cell carcinoma. The most common tumor responsible for hypoglycemia in the thorax is solitary fibrous tumor of the pleura. Brachial plexopathy and pupillary constriction are more likely to occur with superior sulcus tumor.

A. Miliary TB represents diffuse hematogenous spread of the tuberculin bacillus throughout the lungs. The radiographic appearance is that of tiny 1-2 mm nodules throughout the lungs. Our case has much more numerous micronodules than seen in miliary TB.
B. Correct. Correct. Pulmonary alveolar microlithiasis (PAM) is a rare condition of uncertain etiology. The chest radiograph shows numerous very fine micronodules throughout both lungs, more so in the middle and lower lung zones. The radiographic findings have been described as that of a sand-storm like appearance. Our case has classic features seen in PAM.
C. Lymphangitic carcinomatosis is characterized by metastatic tumor involvement of the lymphatic system. The typical chest radiographic findings include reticulonodular or linear opacities, septal lines and mediastinal or hilar adenopathy. These features are absent in our case.
D. Idiopathic pulmonary hemosiderosis is a rare disease of unknown etiology. It most commonly occurs in children in their first decade of life. It is seen as diffuse airspace opacities following an episode of acute hemorrhage. As the blood products break down, there is deposition of hemosiderin into the pulmonary interstitium and lymphatics. Thus, the radiographic findings following repeated bouts of bleeding appear as a reticular pattern. These features are absent in our case.

Findings: Diffuse cystic lung disease. Lungs are uniformly involved with no evidence of architectural distortion.

A. Centrilobular emphysema which occurs in smokers is recognized by the presence of multiple lucencies which are predominant in the upper lobes. Characteristically these areas of centrilobular emphysema do not have well defined walls and therefore can be differentiated from cysts. Upper lobe predominance is a key feature and differs from the test case in which there is diffuse involvement.
B. Correct. Lymphangioleiomyomatosis. This disease occurs in young to middle-aged women of reproductive age. It is characterized by the presence of cysts with well-defined thin walls measuring 1-2 mm in diameter. The distribution is usually diffuse and other features of interstitial lung disease or fibrosis are notably absent, i.e. reticulation, small nodules, honeycombing and traction bronchiectasis. There is no evidence of architectural distortion.
C. Langerhans cell histiocytosis does occur in smokers but is characterized by a number of different features. Nodules up to 1 cm in diameter are common. These nodules frequently cavitate and in the end state of the disease a cystic pattern can be noted. However, a purely cystic pattern is extremely unusual. Upper lobe involvement predominates, and the bases, particularly the costophrenic angles are free of disease, a feature which is not present in the test case.
D. CT features of lymphoid interstitial pneumonia include ground glass attenuation, centrilobular and subpleural lung nodules with thickening of the interlobular septa and peribronchovascular interstitium. Perivascular cysts are seen in a minority of cases. Most of these CT features are not present in the test case. The cysts are diffuse and not perivascular in location.

A. Correct. Bronchioloalveolar carcinoma. False-negative studies in primary lung cancer (negative PET which proves to be a tumor) are unusual but may be seen with small (less than 10 mm) in diameter lung cancers. False-negative examinations also occur in lung malignancies of low metabolic activity. Such tumors include both bronchioloalveolar carcinoma and carcinoid tumors. Another cause of a false negative PET study is the presence of hyperglycemia in the patient being studied.
B. Incorrect.
C. Incorrect.
D. Positron emission tomography (PET) with F-18 labeled fluorodeoxyglucose is a glucose analogue label with positron emitting fluorine 18. It is a useful imaging modality in evaluating patients with lung cancer. PET takes advantage of one of the characteristic features of malignant cells, increased glucose metabolism. Because most malignant tumors are metabolically active, tumor cells take up increased amounts of FDG relative to normal lung tissue. The tumors listed in choices B to D are all malignant, highly metabolically active tumors, and would be expected to be positive on FDG/PET imaging.

Findings: Uniform low attenuation in both lungs with paucity of pulmonary vessels, which are attenuated peripherally.

A. Paraseptal emphysema is characterized by multiple areas of subpleural emphysema often with visible thin walls that correspond to interlobular septa. The emphysema is localized in the subpleural zones and along the interlobar fissures.
B. Correct. Panacinar or panlobular emphysema is characterized on high-resolution CT by the presence of fewer and smaller than normal pulmonary vessels. The lungs appear of low attenuation and usually measure less than minus 910 Hounsfield units. Panacinar emphysema is almost always more severe in the lower lobes but may appear diffuse. In this case, the extensive lung destruction associated with paucity of peripheral vessels is readily detectable. This type of emphysema is characteristically identified in patients with alpha one antitrypsin deficiency.
C. Centrilobular emphysema is characterized on high-resolution CT by the presence of multiple small round areas of abnormally low attenuation several millimeters to a centimeter in diameter and distributed throughout the lung but usually with an upper lobe predominance. This is in contradistinction to the current case where the involvement is more marked at the bases of the lungs and individual well defined lucencies cannot be identified. The lucencies in centrilobular emphysema tend to be multiple, small and spotty. Centrilobular emphysema may become more severe and the areas of lung destruction may become more confluent and the centrilobular distribution may no longer be recognizable. The HRCT appearance can then closely simulate panlobular emphysema. However, such severe disease would not be expected in a 40-year-old. The development of centrilobular emphysema is directly related to smoking and is much more commonly seen in individuals in the sixth and seventh decades of life.
D. Paracicatricial or irregular emphysema is focal emphysema usually found adjacent to parenchymal scars, in diffuse pulmonary fibrosis and in the pneumoconiosis, particularly when progressive massive fibrosis is present. It is usually recognized on CT when associated fibrosis or scarring is identified. There is no evidence of fibrosis either focal or diffuse in the demonstrated case.

"A. Not typically associated with effusions or lymphadenopathy. Commonly manifests with ground glass and upper-lobe predominant cystic changes.

A. As there is no homogenous layering water attenuation fluid present in the pleural space.

A. Usually these pulmonary lesions are small nodules that are less than 1 cm in diameter with surrounding inflammatory changes.

A. These infections are not commonly reported in patients with cystic fibrosis.

A. Hemorrhage may occur as a result of low platelet count, vasculities and drug toxicity. However in this case there is no hemoptysis which makes it less likely.

B. The images show bilateral hilar adenopathy in a young individual. The history and radiographic findings suggest diagnosis of sarcoidosis. Staging of sarcoidosis is based on findings noted on the chest radiographs.

A. Circumferential thickening of the trachea with ulcer formation and tracheal luminal narrowing/stenosis are typical features seen in Wegener granulomatosis when the airway is involved. The other features are not seen.

A. Incorrect.
B. Incorrect.
C. Incorrect.
D. Correct. The images show well-defined cysts within both lungs with preservation of the lung architecture. The findings are suggestive of Lymphangioleiomyomatosis (LAM). Chylothorax and recurrent pneumothorax are associated with LAM. The other options are not associated with LAM.

A. Correct. PCP appears as ground glass opacities within both lungs, predominantly in both upper lobes. The finding is typically symmetric in nature. Well defined cysts or pneumotoceles are also present. Given the above findings, PCP is the correct answer.
B. Wegener granulomatosis typically appears as nodules with or without cavitation in the lungs. This finding is not shown in the provided images.
C. HP appears as centrilobular ground glass opacities in both lungs. This finding is not shown in the provided images.
D. PAP appears as ground glass opacities with superimposed intralobular septal thickening. This pattern has been called the crazy-paving pattern. This finding is not shown in the provided images.

A. Incorrect.
B. Correct. Images show an isodense lesion within the trachea. One of the most common endotracheal lesion is squamous cell carcinoma. The image provided is consistent with a tracheal tumor.
C. Tracheomalacia represents collapse of the trachea on expiration. This finding is not shown in the provided images.
D. Amyloidosis causes circumferential thickening of the trachea with possible calcification. This finding is not shown in the provided images.

A. Pulmonary fibrosis produces stiff noncompliant lungs that may require high pressures to ventilate, but because the lungs are not particularly stretched barotrauma is uncommon. Acute lung injury and COPD carry a much higher risk of barotrauma.
B. Correct. In barotrauma air initially escapes into the interstitial spaces of the lungs and tracks along the bronchovascular bundles toward the mediastinum. Pneumomediastinum and pneumothorax may occur subsequently.
C. Between 60 and 90% of pneumothoraces in patients on positive pressure ventilation are under tension.
D. Tracheal tears may occur in the ICU setting secondary to traumatic intubation or after blunt trauma or penetrating but not barotrauma.

A. Correct. In fact, in the era of MDCT, we are beginning to detect more of these as a manifestation of minimal TAI. In these patients, beta blockers may be the only treatment needed.
B. Most aortic injuries seen on CT will be detected within the aortic isthmus.
C. An isolated anterior mediastinal hematoma is almost never associated with TAI. Usually these are from sternal fractures.
D. In fact, these are commonly encountered in the CT of TAI.

A. The differential diagnosis for a tree-in-bud pattern includes infectious bronchiolitis (from any type of infection), aspiration and diffuse panbronchiolitis.
B. Correct. Poorly defined centrilobular nodules are the hallmark of small airway inflammation.
C. The vessels in the areas of decreased attenuation tend to be of smaller caliber.
D. This is a feature of organizing pneumonia. Obliterative bronchiolitis tends to present with a mosaic attenuation pattern.

A. Correct. Sternal dehiscence is an uncommon but serious complication of median sternotomy. Displacement or shift of the sternal wires on chest radiographs is considered a highly specific sign of sternal dehiscence. Fracture and rotation of sternal wires are not thought to play a significant role in dehiscence. Resorption of wire does not occur. Studies have shown that sternal wire abnormalities usually precede the clinical detection of dehiscence by 1-3 days.

A. Incorrect.
B. Incorrect.
C. Correct. Castleman's and Castleman's disease is also referred to as angiofollicular lymph node hyperplasia. It is a disease of unknown etiology. Two forms of the disease have been described, hyaline-vascular type and the plasma-cell type. On contrast-enhanced CT scan, adenopathy in Castleman's disease demonstrate dense contrast-enhancement.
D. Whipple's lymph nodes may demonstrate central fat attenuation.

A. Solid nodules are most numerous, but have been foound to have a lower rate of malignancy in screening studies. (See reference).

A. Correct. This is the typical finding of DIP. 

B. Correct. Morgagni hernia represents a congenital diaphragmatic defect. They occur in the right cardiophrenic angle. The hernia sac usually contains intraabdominal fat and may contain air filled loops of bowel.

A. Though the lesion is round, and well-circumscribed, this lesion does not contain fat, which would be diagnostic for hamartoma. The calcifications are chunkier than the classic popcorn calcifications of pulmonary hamartoma. Usually, hamartomas have no effect on adjacent airways. The net result is that hamartoma is possible but not the most likely.
B. Correct. The affiliation with the airway, round nature and chunky eccentric calcifications are very typical for pulmonary carcinoid tumors. In fact, 40% of carcinoids may be calcified on CT. Another feature of carcinoid tumors is their effect on the airway (seen in up to 50% of cases). In this case, the effect is air-trapping.
C. These lesions may be anywhere in the lung but tend to be peripheral. They may present with areas of ground glass and somewhat spiculated borders. Smaller lesions may be smooth-bordered and round. Calcifications may be eccentric in adenocarcinomas. Usually adenocarcinomas do not result in air-trapping.
D. Granulomas tend to be smaller than 2 cm and are usually calcified. When calcified, they are entirely calcified, centrally calcified or lamellated. Airway effects from granulomas are rare. Though this lesion could be a granuloma, its CT appearance is not suggestive of one.

A. The most common radiographic manifestation of pulmonary alveolar proteinosis is ground glass and air space opacities which are located in a perihilar distribution such as in this case. The presence of ground glass opacities on the CT scan is consistent with pulmonary alveolar proteinosis. However, septal thickening is not prominent. The combination of ground glass opacities and septal thickening is sometimes referred to “crazy paving,” an appearance most commonly seen in pulmonary alveolar proteinosis. The CT also demonstrates the presence of multiple relatively thin walled cysts. Such cysts are not a feature of pulmonary alveolar proteinosis.
B. Although the standard radiograph is somewhat suggestive of the “butterfly” or “bats wing” pattern identified in cardiogenic pulmonary edema, the heart is not enlarged and there is no evidence of Kerley B lines or pleural effusions. Multiple thin walled cysts are not a feature of congestive heart failure.
C. IPF occurs in patients between 50 and 70 years old. Radiographic findings include reticular opacities in the peripheral distribution at the lung bases. Thus, the presence of perihilar disease in our case, along with absence of disease in the subpleural basilar location, leads us away from the diagnosis.
D. Correct. In patients with PCP, the chest radiograph classically demonstrates bilateral often perihilar reticular and ground glass opacification which may eventually become confluent and produce air space consolidation within several days. Cysts are visible on chest radiographs in 10% of patients although they are appreciated far more commonly on HRCT scans (33%). Cysts may occur in the acute or post infective period and range in number, size, shape and distribution. They are commonly multiple and have a predilection for the upper lobes. Spontaneous pneumothorax may be a feature of PCP infection and occurs in approximately 35% of patients with cysts.

D. Correct. Kerley B lines are short horizontal lines that are visible on chest radiograph adjacent to the costophrenic sulcus. They are approximately 1 to 2 cm long and are noted to extend to the pleural surface. They represent thickened interlobular septa and are visible in patients with lymphangitic arcinomatosis and pulmonary edema.

A. Boerhaave’s syndrome represents perforation of esophagus following severe episodes of vomiting. In this instance, pneumomediastinum rather than pneumothorax is the expected consequence.
B. Recurrent pneumothorax may be associated with chronic infiltrative lung disease of any cause, but the prevalence is particularly high in two diseases; Langerhans cell histiocytosis (histiocytosis x) and lymphangioleiomyomatosis. Both of these entities are characterized by the presence of multiple lung cysts which may rupture through the visceral pleura causing a complicating pneumothorax. However, pneumothorax may be seen as a complication of the late stages of other types of infiltrative lung diseases that are associated with fibrosis and honeycombing. Desquamative interstitial pneumonia is not characterized by the presence of cysts. High resolution CT frequently demonstrates ground glass and alveolar opacities more marked in the mid and lower lung zones. Fibrosis and honeycombing are not features and the disease responds to steroid therapy.
C. Correct. Malignant neoplasms, particularly metastatic sarcoma, are occasional causes of spontaneous pneumothorax. The most common tumor type is metastatic osteogenic sarcoma. The mechanism for the development of pneumothorax is not clear, but it may be related to the presence of cavitation and subsequent rupture into the pleural space. The presence of a “spontaneous” pneumothorax in a child in the setting of a primary osteogenic sarcoma should prompt a CT examination to search for the presence of metastatic disease.
D. Pneumothorax which is unresponsive to chest tube drainage can be a feature of a ruptured bronchus which is sustained following blunt trauma usually in high speed motor vehicle accidents. However, the rupture must occur at a site in the bronchus which is contained within the mediastinal pleura. Thus tears close to the carina produce pneumomediastinum rather than pneumothorax.

"B. Correct. Allergic bronchopulmonary aspergillosis is a complex hypersensitivity reaction to aspergillus organisms colonizing the bronchial lumen. The inflammatory reaction results in cellular infiltration and release of proteolytic enzymes which produce tissue damage in the bronchial wall. Excessive mucus production leads to mucoid impaction of the airways. The radiographic hallmark is central bronchiectasis. Air-crescent sign, pleural thickening, and halo sign are not features of allergic bronchopulmonary aspergillosis.

 

  

A. Diffuse panbronchiolitis is a proliferative bronchiolitis that occurs mostly in Asians. It is an acute cellular bronchiolitis with inflammatory exudates in the small airways. It usually occurs between the fourth and seventh decades and is characterized by chronic inflammation in the respiratory bronchioles. Panbronchiolitis is likely infectious in etiology and responds to treatment with erythromycin although the exact causative agent has not been identified. There is no evidence of any increased prevalence in smokers.
B. Usual interstitial pneumonitis is one type of chronic interstitial pneumonia that is usually idiopathic (idiopathic pulmonary fibrosis) although it may be caused by toxic drugs, environmental exposure, and collagen vascular disease. It is characterized by the development of relentlessly progressive fibrosis and is associated with 2-3 year median length of survival from the time of diagnosis. No association with smoking has been established and there is no evidence of any increased prevalence among chronic smokers.
C. Lymphocytic interstitial pneumonia is a benign lymphoproliferative disorder characterized by ground-glass attenuation, centrilobular and subpleural lung nodules with thickening of the interlobular septa, and peribronchovascular interstitium. Perivascular cysts are seen in a minority of cases. No association with smoking is reported.
D. Correct. Desquamative interstitial pneumonia is characterized by the histologic feature of intraalveolar macrophagic accumulation. In most cases it is associated with cigarette smoking and is thought to represent the end of a spectrum of respiratory bronchiolitis—associated interstitial lung disease. It affects cigarette smokers 30-40 years old with a male to female ratio of 2:1. Bronchoalveolar lavage fluid contains increased numbers of alveolar macrophages with granules of “smoker’s pigment.” The prognosis for patients with DIP is good with cessation of smoking and steroid therapy.

A. Systemic lupus erythematosus (SLE. is a multisystem autoimmune disorder. Radiologic abnormality can involve the lungs, pleura, and the heart but do not involve the esophagus. Parenchymal disease may manifest as acute lupus pneumonitis, which is characterized as unilateral or bilateral air space disease or pulmonary hemorrhage. The incidence of interstitial fibrosis is very small in patients with SLE. The findings in the test case do not favor this diagnosis.
B. Sarcoidosis is a chronic granulomatous disease. It is predominantly an upper lung disease. It tends to be bilateral and fairly symmetric. Esophageal involvement is rare. The findings of basilar reticular opacities and dilated esophagus lead us away from this diagnosis.
C. IPF affects patients between 50 and 70 years old. Radiographic findings include reticular opacities in the peripheral distribution at the lung bases. Esophageal involvement is not reported. Thus, the presence of esophageal involvement and the young age of the patient in the case lead us away from this diagnosis.
D. Correct. Scleroderma is a connective tissue disorder that involves the pulmonary parenchyma, skin and GI tract. Pulmonary complications are the most common cause of death in these patients and pulmonary fibrosis is a frequent pulmonary manifestation. Esophageal involvement occurs in more than 50% of patients. Thus the combination of esophageal involvement and pulmonary changes are virtually pathognomonic of scleroderma.

A. Correct. The bronchiole forms the center of the lobule with its accompanying pulmonary artery. 

A. Bronchogenic cancer is considered in the differential diagnosis of a solitary pulmonary nodule/mass. They can have varying radiographic appearances. They tend to be present in the upper lobes and or centrally either within the airways or perihilar region. They can be lobulated, spiculated or can also cavitate. However, presence of fat in the nodule/mass as in our case suggests an alternative diagnosis. Thus, Bronchogenic cancer is the incorrect answer.

A. Correct. Centrilobular nodules occur in the center of the secondary lobules, are usually ground glass in nature and are equidistance from each other. These features are present in the provided image. 

A. Diffuse cystic lung disease, cysts are usually uniform in size. Here, cysts significantly differ in size: upper lobes compare to lower lobes. No definitive association with collagen vascular disorders.

A. Lymphangitic carcinomatosis appears as thickening of the interlobular septa and peribronchovascular bundle, often with a nodular appearance. These features are not present in the provided images.

A. Mesothilioma appears as a rind of tissue that encircles the hemothorax. This features is not present in the provided images.

A. Pulmonary Langerhans Cell Histiocytosis (PLCH) affects typically affects young smokers 20-40 years of age. PLCH involves primarily the mid and upper lung zones, and presents as a combination of reticulonodular pattern, air cysts, and irregular nodules. In this case, there is an absence of associated nodules expected in LCH.

A. Respiratory bronchiolitis (RB) is a smoking related interstitial lung disease characterized by upper lobe predominant centrilobular nodules in the background of emphysema. The nodules associated with RB tend to be far smaller than those seen in this case.

A. Incorrect.

A. Incorrect.

A. It is characterized by proximal weakness, a result of an abnormality in the release of acetylcholine at the neuromuscular junction. About 50% of the cases have an associated small cell cancer. Clinical manifestation frequently precede cancer identification. In most cases, cancer is discovered within the first two years after the onset of syndrome.

A. Streptococcus pneumoniae is the most common cause of pneumonia in AIDS patients.
B. It typically occurs when CD4 count is in the range of 200-500 cells/uL.
D. Majority of AIDS related lymphoma are non-Hodgkin's which usually present as nodules or masses with air bronchograms in the lungs.

A.
B. They represent right to left shunt and thus paradoxical embolizations can occur.
C. Majority of them are found in the lower lobes.
D. A simple AVM representing a nidus connecting one artery and one vein are more frequent.

"A. ""Shrinking lung"" syndrome represents progressive loss of volume and is a common manifestation of systemic lupus erthematosus. The exact etiology is unclear, however, it is believed to be due to diaphragmatic dysfunction or due to restriction of respiration secondary to pleuritic chest pain. Radiographs show progressive loss of volume in both lower lobes.

A. The smoothly-marginated left paraspinal mass on the chest radiograph and corresponding high signal posterior mediastinal mass on the T2-weighted MRI are typical of an esophageal duplication cyst. There is no extension into the spinal canal and no evidence of bone or disc destruction.
B. The smooth borders of the mass on the chest radiograph and the MRI as well as the normal adjacent vertebral bodies and disc space argue against tuberculosis. Furthermore, one would expect a patient with spinal tuberculosis to have a fever.
C. The homogeneity of the lesion, the lack of spinal invasion, and the patient's age all speak against this diagnosis.
D. The lack of extension into the spinal canal and the absence of vertebral anomalies argues against a neurenteric cyst.

A. The images demonstrate a anomalous left pulmonary artery arising from the right pulmonary artery and coursing between the esophagus and the aorta (left pulmonary artery sling). Butterfly vertebra are associated with Alagille syndrome which can also cause peripheral pulmonary artery stenoses but are not associated with pulmonary artery sling.
B. There is an anomalous origin of the left pulmonary artery from the right pulmonary artery. The left pulmonary artery courses between the trachea and the esophagus (pulmonary artery sling). Pulmonary artery slings are associated with tracheal stenoses due to complete cartilaginous tracheal rings.
C. There is an anomalous origin of the left pulmonary artery from the right pulmonary artery. The left pulmonary artery courses between the trachea and the esophagus (pulmonary artery sling). Hypercalcemia is associated with Williams syndrome. Williams syndrome is associated with supravalvular aortic stenosis, pulmonary stenosis, and mitral valve regurgitation, but not with pulmonary artery sling.
D. There is an anomalous origin of the left pulmonary artery from the right pulmonary artery. The left pulmonary artery courses between the trachea and the esophagus (pulmonary artery sling). Hypoplasia of the right lung can be seen in scimitar syndrome. Scimitar syndrome is associated with hypoplastic right pulmonary artery but not with pulmonary artery sling.

B. Correct. It is situated between the aortic arch and the left pulmonary artery. The space contains mediastinal fat, ductus ligament, nodes and the left recurrent laryngeal nerve. Thus, mass in this location can involve the left recurrent laryngeal nerve resulting in vocal cord abnormalities, including hoarseness.

A. Eccentric calcification can be identified in small percentage of lung carcinomas which may incorporate adjacent calcified granulomas or they may themselves calcify. In these instances, the calcification is often stippled or punctuate.
B. Lesions such as hamartoma and granuloma have a much lower diagnostic accuracy.
C. Increased glucose metabolism in lesions result in increased uptake and accumulation of FDG. Thus, metabolically active lesions will demonstrate increased FDG uptake. The degree of FDG accumulation is measured using standardized uptake ratio (SUR). Typically, lung cancers demonstrate SUR of greater than 2.5. For nodules greaterthan 1 cm, FDG-PET has sensitivity of about 95%. However, its role in evaluation of SPN should be approached with caution. The reason is infectious (granulomas) and inflammatory solitary pulmonary nodules can demonstrate increased FDG uptake and thus may give false-positive results.
D. Doubling time of less than one month suggest a very high doubling time and is suggestive of infection.

"C. Bronchial artery originates from the aorta or intercostal arteries. They travel from the pulmonary hila to the level of the terminal bronchioles within the peribronchovascular interstitium.
D. The secondary pulmonary lobule is a hexagonal shaped structure measuring about 1-2.5 cm. The wall (interlobular septa) of the lobule contains connective tissue, pulmonary vein and lymphatics. The central portion of the lobule contains pulmonary artery and terminal bronchiole.

B. Bronchogenic cysts are congenital lesions thought to originate from the primitive ventral foregut and may be mediastinal, intrapulmonary, or, less frequently, in the lower neck. Approximately two-thirds are within the mediastinum, and one-third is intraparenchymal. They account for 40%–50% of all congenital mediastinal (intrathoracic) cysts, and there is a slight male predominance. The frequency of bronchogenic cysts is unknown presumably because most patients are asymptomatic. Numerous studies have documented the rare frequency of bronchogenic cysts, with an average incidence of 20 cases over a 20-year period. The cysts contain mucoid material and are lined by ciliated columnar or cuboidal epithelium. Their walls contain smooth muscle and often cartilage. They are sometimes intrapulmonary, typically in the medial third of the lung. If in a mediastinal location, they may be paratracheal (usually right-sided), carinal, or hilar. The carinal location is most frequent.

Findings: On this lateral chest radiograph, there is anterior displacement and bowing of the trachea by a mediastinal opacity occupying Raider triangle, the clear space above the aortic arch bordered by the vertebral column and posterior to the trachea and esophagus.

A. The abnormality shown in the chest radiograph is caused by the aberrant course of a subclavian artery. In patients with a left aortic arch with normal origin of the great vessels or in patients with a right aortic arch with mirror image branching, the great vessels do not cause this appearance.
B. This is the most common of the aortic arch vessel anomalies. In these cases, the right subclavian artery does not arise from the innominate artery but originates as the last branch from the aortic arch. The aberrant subclavian then takes a retroesophageal route to its destination. The aberrant right subclavian artery frequently arises from a dilated segment of the proximal descending aorta, the diverticulum of Kommerell, which can be mass-like on conventional radiography.
C. This abnormality occurs when the left main pulmonary artery arises from the right pulmonary artery instead of originating from the main pulmonary artery. The left pulmonary artery courses cephalad to the right mainstem bronchus, and travels between the trachea and esophagus to supply the left lung. On barium esophagram, the aberrant left pulmonary artery causes an anterior impression on the mid-esophagus. The abnormality in this case lies at and above the aortic arch whereas the pulmonary arteries lie below the aortic arch.
D. The classic double aortic arch anatomy develops when involution of the distal right fourth arch does not take place. The right and left aortic arches encircle the trachea and esophagus. Double aortic arch is better appreciated on the PA chest radiograph.

A. The superior vena cava contributes to the most superior aspect of the anterior border of the mediastinum on a lateral chest radiograph.
B. The inferior vena cava contributes to the most inferior aspect of the posterior border of the mediastinum on a lateral chest radiograph.
C. The main pulmonary artery contributes to the anterior border of the mediastinum on a lateral chest radiograph, and represents the superior portion of the convex curve largely created by the right ventricle.
D. The right atrium is not typically seen in the lateral projection, but represents the inferior aspect of the right border of the mediastinum on a frontal chest radiograph.

"A. Correct. The posterolateral Bochdalek diaphragmatic hernia is usually large and associated with considerable mass effect on the developing lung. The anteromedial Morgagni hernia is typically small and most often asymptomatic. Bochdalek hernia is strongly associated with pulmonary hypoplasia whereas hypoplasia is usually not a feature of the Morgagni defect. Occasionally Morgagni hernia may be large or bilateral often with herniation into the pericardial sac with cardiorespiratory compromise.
B. Correct. Potter syndrome was originally described as renal agenesis in association with fetal anuria and oligohydramnios. Bilateral pulmonary hypoplasia is thought to be caused by extrinsic compression of the fetal thorax by the uterus in association with decreased amniotic fluid. Other causes of olgohydramnios including bilateral urinary obstruction, bilateral cystic or dysplastic kidneys and prolonged amniotic fluid leak have also been found to be associated with pulmonary hypoplasia. Thoracic cage compression, most commonly due to bone dysplasia and intrathoracic lung compression, notably associated with congenital diaphragmatic hernia, pleural fluid or a large thoracic or abdominal mass are also causes of bilateral pulmonary hypoplasia. Additional etiologic factors in bilateral pulmonary hypoplasia are conditions associated with decreased fetal breathing (e.g. myotonic dystrophy, myasthenia gravis, hypotonia) and decreased pulmonary blood flow, such as inTetralogy of Fallot and pulmonary atresia.
C. Vascular ring is a result of abnormal vascular and ligamentous mediastinal structures, with encirclement of the trachea and esophagus. The symptomatic vascular ring typically causes compression of the trachea and presents with respiratory distress and repeated episodes of pneumonia. However, this abnormality is not associated with pulmonary hypoplasia.
D. A tracheal bronchus describes the situation where the right upper lobe, or one of its segments, is supplied directly from the trachea, rather than as a branch of the right mainstem bronchus. When the bronchus supplies the entire lobe, it is termed a ""bronchus sui"" or pig bronchus, as this is the normal porcine anatomical arrangement. The tracheal bronchus may be asymptomatic and discovered incidentally, or may be associated with repeated right upper lobe infections. Its incidence is reported as 0.1 - 2% of the population, and is associated with rib anomalies and Down syndrome. However, it is not associated with pulmonary hypoplasia.

A. Anomalies of the aortic arch and the great vessels are relatively common, seen in up to 3% of the population. The frontal chest radiograph in this case demonstrates indentation along the right side of the trachea from the right aortic arch. A smooth-bordered impression is noted along the posterior aspect of the esophagus on the oblique radiograph obtained during barium esophagram. This represents an aberrant left subclavian artery, which courses posterior to the esophagus. Mirror image branching of the great vessels is much less common in patients with a right aortic arch and such patients will have a normal esophagram. An aberrant left subclavian artery may also result in a posterior impression on a barium esophagram. However, in this case the aortic arch is located to the right of the trachea.  
B:  Patients with mirror image branching are much more likely to have additional congenital cardiac anomalies, usually tetralogy of Fallot or truncus arteriosus.
D. Pulmonary artery sling is a term used to describe anomalous origin of the left pulmonary artery from the right pulmonary artery. This anomalous vessel (the sling) passes between the trachea and the esophagus on its way to supply the left lung. On esophagram, this results in an anterior impression on the esophagus. In this case, there is a right aortic arch as well as posterior impression on the esophagus indicating an aberrant left subclavian artery.

A. While this is certainly a possibility by imaging findings, the patient had no symptoms or signs to suggest this by history.
B. This relates to a post myocardial infarction (MI) pericarditis. The imaging findings on Dressler syndrome include pleural and pericardial effusion. Dressler syndrome does not occur immediately following an acute MI.
C. The lobar distribution argues against heart failure. Cardiogenic pulmonary edema is typically bilateral and symmetric in distribution.
D. In the setting of acute mitral regurgitation, the regurgitant jet from the mitral valve is directed toward the ostium of the right superior pulmonary vein. In patients with acute myocardial infarction that affects the mechanics of the papillary muscles or in the setting of acute papillary muscle or chordae tendinae rupture, the acute onset of mitral regurgitation may present as lobar edema localized to the right upper lobe.

"A. The key is to understand that this is upper and peripheral in its predominace and that the patient has had an indolent course.
B. The time course and distribution would not favor edema.
D. The time course of 2 months would not be concordant with a community acquired pneumonia.

Terminology
Idiopathic chronic condition marked by alveolar filling with mixed inflammatory infiltrate that consists largely of eosinophils

Imaging Findings
Chronic peripheral upper lobe consolidation (photographic negative of pulmonary edema) (25%)
Consolidation , homogeneous (100%)
Upper lung zones (40%)
Peripheral (85%)
Resolution (or natural evolution) tends to be from outside to inside of consolidated lung
Relapse or recurrence: Same place, same size, same shape

Clinical Issues
Average duration of symptoms 7.7 months before disease diagnoses
Blood eosinophilia common ( 90% ), although its absence does not exclude diagnosis
Most patients relapse after steroid withdrawal (80%)

Diagnostic Checklist
Peripheral bands or lines that parallel chest wall

A. That entity would result in unilateral left hilar enlargement
B. That entity would result in enlargement of the left atrial appendage which should be below the mainstem bronchus on the frontal projection.
C. Both pulmonary arteries are enlarged with peripheral pruning. On the lateral, one can more easily see pulmonary artery atherosclerosis
D. The abnormal contour is more inferior than a post-traumatic aneurysm.

B. Radiation pneumonitis is a complication of radiation therapy. Multiple factors determine the development and appearance of pneumonitis. They include, the volume of lung involved, the type of radiation used, the time period over which radiation therapy was given, whether chemotherapy was given at the same time, and whether there was preexisting lung disease to name a few. Radiation pneumonitis is divided into early and late manifestations. The early or acute pneumonitis occurs within 1 to 3 months following treatment and radiographically appears as homogeneous or patchy ground glass opacities, lucencies and volume loss. The changes evolve over the next 6 to 12 months and usually become stable within 2 years. They appear radiographically as dense consolidation, traction bronchiectasis and volume loss.

Desquamative: Insidious onset, Best diagnostic clue: Smoker with HRCT showing diffuse ground-glass opacities

"D. It is characterized by abnormal cilia structure and function and thus is also known as Dyskinetic cilia syndrome. Patient's have abnormal mucociliary clearance and repeated pulmonary infections. As a result, they develop bronchiectasis which is typically present in the lower lobes. They also get sinusitis and about half of them have situs inversus. The combination of bronchiectasis, situs inversus and sinusitis is called Kartagener's syndrome.

Williams-Campbell syndrome: Central Bronchiectasis
Lemierre syndrome: Post-anginal sepsis or necrobacillosis, uncommon but potentially life-threatening complication of acute pharyngotonsillitis

Terminology
Primary ciliary dyskinesia: Genetic disorder of ciliary structure resulting in impaired mucociliary clearance
Kartagener syndrome: Situs inversus, sinusitis, bronchiectasis

Imaging Findings
CT & HRCT
Bronchiectasis, bronchial wall thickening
Centrilobular nodules, tree-in-bud opacities
Mucus plugs, bronchial air-fluid levels
Peribronchial airspace disease
Radiography
Hyperinflation
Bronchial wall thickening, bronchiectasis
Atelectasis, consolidation
Situs inversus or dextrocardia (50%)

Clinical Issues
M:F = 1:1
Typical presentation in early childhood, but many patients are symptomatic since birth
Recurrent rhinosinusitis, otitis, and pulmonary infection; male infertility
Good prognosis with aggressive prophylaxis and treatment

"A. The presence of symmetric patchy opacities, volume loss of upper lobes and calcified mediastinal and hilar nodes is a fairly classic appearance of sarcoidosis.

CF: Predominately upper lobe bronchiectasis and mucus plugging in hyperinflated lungs
Amyloid: Diffuse septal thickening + nodules (± calcification) + adenopathy (± calcification)

C. Pulmonary artery aneurysms are rare. They may occur secondary to infection (septic emboli, tuberculosis etc.), catheter-related complications, pulmonary hypertension or vasculitidies. The most common cause is probably catheter-related complications. Rasmussen aneurysm is a mycotic aneurysm that occurs in relation to tuberculus infection.

A. Lymph nodes in Castleman's disease are typically enhancing nodes.
B.
C.
D. Necrotic lymph nodes are commonly seen in patients with tuberculosis.

A. Performed to diagnose cystic fibrosis.
B. Often elevated in patients with sarcoidosis
C. Allergic bronchopulmonary aspergillosis results from Type I (IgE-mediated) and Type III immunologic response to the endobronchial growth of aspergillus. The inflammatory reaction results in cellular infiltration and release of proteolytic enzymes which produce tissue damage in the bronchial wall. Excessive mucus production leads to mucoid impaction of the airways. The radiographic hallmark is central bronchiectasis. IgE levels are elevated in patients.
D. Used to diagnose Wegener's granulomatosis.

A. Recommendation is follow-up CT scan for a low risk patient with 5 mm nodule. However, this patient is high risk as she has history of melanoma. Recommendations do not apply.
B. Incorrect.
C.
D. The recommendations do not apply in a patient with a known underlying malignancy.

"A. It is best thought of as a small vessel vasculitis. Takayasu and Giant cell are the large vessel vasculitides.
B. This triad is seen in only a small minority of patients.
C. This is seen in up to 90% of patients.
D. It is usually concentric.

Imaging Findings
Best diagnostic clue: Multiple cavitary lung nodules & large airway narrowing
50% of lung nodules & masses cavitate
Focal or multifocal consolidation can also cavitate
Patterns: Cavitary nodules, focal consolidation & diffuse airspace disease from hemorrhage
Subglottic stenosis often visible, but overlooked on chest radiography
Pleural effusion: 20%, pneumothorax rare

Pathology
Etiology: Unknown, suspect inhaled antigen
Necrotizing vasculitis & granulomatosis in lung nodules, associated hemorrhage common
Subglottic stenosis, tracheobronchial stenosis & ulcerating tracheobronchitis
Focal necrotizing glomerulonephritis

Clinical Issues
Most common signs/symptoms: Sinusitis, rhinitis & otitis media
Classic Wegener triad: Sinus, lung & renal disease
Renal failure: Most common cause of death
With systemic glucocorticoids & cyclophosphamide
Survival at 24 months: 80%
Disease relapse 50%, drug side effects 42%

A. The most common finding is a normal high resolution CT examination.
C. The chronic form shows reticular opacities in the middle and lower lung zones.

A. Adenoid cystic tumors are far more common in the trachea.
B. In fact, most are malignant.
C. Squamous cell carcinoma is associated with smoking.
D. The carcinoid tumor is more commonly found in the bronchi than the trachea.

B. Idiopathic pulmonary fibrosis affects patients between 50 and 70 years old. It is characterized by the development of relentlessly progressive fibrosis and is associated with 2-3 year median length of survival from the time of diagnosis. Radiographic findings include reticular opacities at the lung bases in peripheral distribution. The confident index increases with the presence of honeycomb cysts in the peripheral and basilar distribution. In non-specific interstitial pneumonia, the predominant CT feature includes ground glass opacities.
D. Represents the reverse halo sign and is seen in cryptogenic organizing pneumonia.

C. Correct.

DDx Retrotracheal Space (Raider's Triangle) Mass
Aberrant Subclavian
Aneurysm, Aortic
Goiter, Mediastinum
Zenker Diverticulum

LESS COMMON
Achalasia
Lymphoma

"A. Correct.
B. Correct.
C. Correct.
D. Correct.

All were marked correct, however:

Findings
Left lateral shift and posterior rotation of the heart into the left hemithorax.
Main pulmonary artery segment is projected further to the left than normal.
Outline aortic of aortic knob completely lost
Straightening of the left heart border.

C. Correct.

"B. Correct.

Dependent on composition and concentration of gas and length of exposure
Nitrogen (corn has 5.5% free nitrates) in the plant undergoes 2 oxidation steps to form NO and then NOâ‚‚
Hours after stored, toxic and lethal levels of NOâ‚‚ develop
NOâ‚‚, heavier than air, settles on top of silage, yellowish-orange in appearance with bleach-like odor
Harvest months, September to October

A. Tracheobronchopathia osteochondroplastica is multifocal submucosal osteocartilaginous nodules protruding into the airway lumen.
D. Tracheobronchomalacia is a condition characterized by excessive collapse of the trachea and bronchi (>50% decrease in the cross-sectional area of the airway on expiratory images) because of the weakness of the airway walls. Some of the causes include prior intubation, trauma, infection anid relapsing polychondritis.

D. The example shows a classic appearance of left lower lobe collapse. One of the causes of lobar collapse is endobronchial tumor. The other choices are very unlikely to give left lower lobe collapse.

Flat Waist Sign

B. Correct. When air-fluid levels are present within the pleural space, they exhibit discrepant lengths of air-fluid levels on orthogonal radiographs. Air within the pleural space can be secondary to gas producing organisms or due to broncho-pleural fistula. Empyema represents infected fluid within the pleural space.

C. Described radiographic findings are consistent with mediastinitis.

Acute mediastinitis appears radiographically as widening of the mediastinum that is usually most pronounced superiorly. If the infection is secondary to esophageal perforation, radiolucent air may be visible within the mediastinum and often extends into the soft tissues of the neck. Formation of a chronic abscess may produce a large tumorlike mediastinal mass often containing an air-fluid level.

"A. The radiographic findings along with the presence of lipoproteinaceous fluid from the bronchoalveolar lavage suggests diagnosis of pulmonary alveolar proteinosis. The treatment for this disease includes whole-lung lavage. Thus, this choice is the most appropriate answer.

C. Smokers typically present in the 3rd or 4th decade of life, while non-smokers may not present until the 6th or 7th decade.

A. It has been shown in the literature that tree-in-bud is synonymous with bronchiolitis. Pathologically it correlates with infected mucoid impacted bronchioles.

"A. In a low risk patient, a nodule <= to 4mm does not need follow-up.

Findings: CT scan shows bronchiectasis within both lungs, particularly in the right middle lobe and lingula. In addition, centrilobular opacities resembling tree-in-bud are noted within both lungs.

A. Allergic bronchopulmonary aspergillosis is a complex hypersensitivity reaction to aspergillus organisms colonizing the bronchial lumen. The inflammatory reaction results in cellular infiltration and release of proteolytic enzymes which produce tissue damage in the bronchial wall. Excessive mucus production leads to mucoid impaction of the airways. The radiographic hallmark is central bronchiectasis.

Findings: Numerous tiny nodules are present within both lungs along the subpleural interstitium, fissures and the peribronchovascular interstitium. The lung bases are spared.

A. The distribution of nodules in metastatic disease are randomly distributed.
B. The distribution of nodules in sarcoidosis are in the perilymphatic distribution. This case has classic features seen in sarcoid.  
C. Miliary tuberculosis presents with tiny 1-2 mm randomly distributed nodules. This appearance is absent in our case.
D. The nodules seen in hypersensitivity pneumonitis are centrilobluar in distribution and have a ground-glass appearance. This pattern and distribution are not present in our case.

Findings: A triangular opacity is seen in the right lower hemithorax on the frontal radiograph. In addition, the trachea is deviated to the right suggesting volume loss in the right lung. The lateral radiograph shows an opacity in the posterior lower aspect obscuring the posterior diaphragm. The constellation of the above findings represents right lower lobe atelectasis.

C. The findings described above are those of right lower lobe atelectasis. When lobar atelectasis is present, further investigation should be performed to evaluate for an endobronchial lesion. CT scan performed on this patient (not shown) showed a lung cancer in right lower lobe bronchus.

Findings: Small calcified nodules are noted along the inner aspect of trachea, protruding into the tracheal lumen.

A. It is a systemic disorder characterized by recurrent episodes of cartilage inflammation. On imaging, thickening of the anterior and lateral tracheal wall is noted. The posterior membrane of trachea is spared. These features are not present in our case.
B. It is a granulomatous infection caused by Klebsiella rhinoscleromatis. This disease primarily affects the upper respiratory tract. In a small percentage of patients, the trachea may be affected. When involved, circumferential thickening of tracheal wall is noted.
C. This is a condition of unknown etiology which is characterized by the presence of multiple submucosal osteocartilaginous nodules along the anterior and lateral wall of the trachea. The posterior wall of the trachea is spared. Our case shows typical features of this entity.
D. It is a granulomatous vasculitis which may involve the upper and lower respiratory tract. Tracheal involvement results in narrowing and thickening of the trachea. Our case does not show those features.

D. Approximately 95% of the patients with Langerhans Cell Histiocytosis have a history of smoking cigarettes. It is characterized by the presence of granulomas containing large number of Langerhans cells and eosinophils, resulting in destruction of lung tissue. It occurs in young adults and the incidence is equal in both males and females. Nodules up to 1 cm in diameter are common. These nodules frequently cavitate and in the end state of the disease a cystic pattern can be noted. The cysts are typically bizarre in shape. The findings of irregular shaped cysts and nodules occur mostly in the upper lobe distribution. The bases, particularly the costophrenic angle, are spared.

"Findings: Chest radiograph shows a small left hyperlucent lung. CT scan of the chest shows decreased attenuation and vascularity in the left lung. In addition, mild bronchiectasis is also noted in the left lung.

A. The radiographic findings present in this case are typical of Swyer-James syndrome. The syndrome is believed to be related to a viral bronchiolitis in childhood. This manifests as a small hyperlucent lobe or lung. The hyperlucency is due to bronchiolar obliteration. Air-trapping on expiration scan is also noted.

Swyer-James Syndrome
Postinfectious obliterative bronchiolitis
Viral
Bacterial
Mycoplasma
Arrest of progressive normal lung growth secondary to vascular compromise
Small hyperlucent lung
Attenuated pulmonary vascularity
Air-trapping during expiration on high-resolution chest CT

Poland Syndrome
Absent/underdeveloped unilateral chest wall
Absent/atrophic pectoralis musculature
Unilateral hyperlucent lung appearance
Other associated anomalies
Ipsilateral syndactyly
Sprengel deformity
Rhizomelia
Absent nipple/breast
Dextrocardia
M > F
Right > left

Congenital Lobar Emphysema
Progressive over-distention of a pulmonary lobe due to obstruction
Not a specific disease but a condition that may result from a variety of etiologies
Left upper lobe: 42%
Lucency and hyperexpansion caused by air in distended alveoli
Majority symptomatic in neonatal period and infancy
50% present in first 4 weeks; 75% in first 6 months

"A. Split-pleura sign is not specific for empyema. It may be seen in any disease that results in pleural inflammation or infiltration of pleura by tumor.
B. Stage IIIB disease is characterized by tumor invasion of mediastinal structures, contralateral mediastinal or hilar lymph adenopathy, supraclavicular adenopathy, and malignant pleural and pericardial effusions.
C. Pleural effusion can be transudative or exudative. Distinction between the two is important as the causes and management of the two differs. Transudative effusion usually result from an increase in the capillary hydrostatic pressure or a fall in the colloid osmotic pressure. Common causes include congestive heart failure and cirrhosis. Exudative effusions are caused by an increase in microvascular permeability as a result of inflammation or tumor. Few causes include infection, malignancy, collagen vascular disease and asbestos exposure.
D. Incorrect.

Contrast-enhanced transverse CT scan shows empyema between thickened parietal (arrowheads) and visceral (arrow) pleural layers: the split pleura sign.

A. Fat embolism syndrome occurs in about 2% of patients with fat embolism. It almost universally occurs following long bone fractures on intra-medullary rod placement. The prognosis is poor in older patients and with more severe injuries.
B. Typically, a pulmonary edema pattern develops radiographically within 24 to 72 hour window after long bone fractures.
C. Fat embolism syndrome presents with a classical clinical triad of hypoxia, and respiratory failure, altered mental status and petechial rash. Free fatty acids released during long bone fractures cause endothelial damage and permeability edema.
D. The fat droplets are microscopic and lodge in the pulmonary capillaries. The fat droplets do not completely obstruct the capillary blood flow because the droplets are fluid in nature. CT scan shows bilateral ground glass opacities which typically resolve in 1 to 3 weeks. Endoluminal filling defect in the pulmonary artery containing fat is rare.

B. Hypertrophic pulmonary osteoarthropathy is a painful periosteal reaction that most commonly involves the hand and feet. It is frequently seen in patients with severe chronic lung disease such as emphysema and lung cancer. Relief of symptoms commonly, follows resection of the primary neoplasm. Pulmonary osteoarthropathy may precede discovery of neoplasm by up to 2 years.

Findings: Small nodules and angled consolidation with high attenuation (calcification). Eggshell calcified mediastinal lymph nodes are also present.

A. Pulmonary amyloid may be parenchymal or related to the tracheobronchial tree. In the former, it tends to be nodular with a subpleural or peripheral predominance. Calcification is common, but the central and angled consolidation seen here would not be typical. In tracheobronchial amyloid, airway narrowing is seen and may be calcified or ossified. Calcified lymph nodes may be seen with this condition. In this case, no airway narrowing was noted. In pulmonary manifestation of systemic amyloid, septal thickening is the predominant feature. That finding is not seen in this case.
B. Fibrosing mediastinitis represents an exuberant fibrotic reaction to fungal antigens (usually histoplasmosis). This is seen with calcified mediastinal lymph nodes and soft-tissue attenuation that tend to narrow vessels and bronchi. In this case, calcified mediastinal nodes are seen, but no compromise of vessels or bronchi is seen. Also, fibrosing mediastinitis and histoplasmosis would not explain the bilateral parenchymal opacities, progressive massive fibrosis.
C. At first glance, the pulmonary manifestations are concerning for lung cancer. However, when combined with the angled, calcified nature of this process, this option seems less likely. There is volume loss here with small nodules bilaterally. This option would not explain this constellation of findings.
D. Correct. The key to this case is that the patient was relatively asymptomatic and had such a terrible chest radiograph. The chest CT and chest radiograph show bilateral angled consolidation, which has calcified. The appearance is great for progressive massive fibrosis (PMF). When combined with the multiple small nodules and the mediastinal calcified lymph nodes (some of which are eggshell calcifications), the differential becomes much narrower. Silicosis and sarcoid would head the list, and, since sarcoid is not an answer, the correct option is silicosis.
E. Chronic aspiration was provided as an option to highlight the high attenuation of the consolidation. In this case, it is due to calcium, not aspirated oral contrast. Though chronic aspiration can be seen with small nodules, they tend to be affiliated with the small airways (not the case here). This option would not explain the calcified lymph nodes.

Findings: Left pneumothorax on initial chest radiograph. Subsequent CT shows bizarrely shaped, well-defined cysts with upper lung predominance. No pleural effusions are seen.

A. Though sarcoid can do anything in the lungs and would have an apical predominance, the dominant finding here is bizarrely shaped cysts. The lack of nodules and mediastinal lymphadenopathy would also make sarcoid less likely in this diagnosis.
B. DIP is affiliated with smoking, but, unlike LCH, DIP has a basilar and a peripheral predominance. The dominant finding would be ground glass associated with fibrosis not well-defined cysts. Because of the apical predominance and the lack of ground glass, DIP is not favored.
C. UIP, like DIP, has a basilar and peripheral predominance. Its hallmark is irregular septal lines and honeycombing. The apical nature of the bizarre cysts and sparing of the bases make UIP highly unlikely in this case.
D. The correct diagnosis hinges on the observation of bizarre-shaped cysts (lucent areas with definable walls) that have an apical predominance. Conceivably, a differential diagnosis could include both lymphangioleiomyomatosis (LAM) and Langerhans’ cell histiocytosis (LCH) of the lung. The apical predominance would favor LCH over LAM, but note that LAM was not an option. The middle age and the lack of pleural effusions support the diagnosis. The history of smoking is important in making the diagnosis, as virtually all cases of LCH of the lung are associated with women who smoke.
E. Emphysema is characterized by apical bullae and is seen in smokers. In this case, however, the apical lucencies have well-defined walls. This is not a feature of emphysema-related bullous disease. Though spontaneous pneumothorax can be seen with emphysema, the well-defined cysts suggest another etiology for the radiographic findings.

Findings: The radiographs and CT demonstrate right-sided circumferential nodular pleural thickening in association with a dominant lobular right anterior mediastinal mass with punctate calcifications. It should be noted that circumferential nodular pleural thickening is typical of pleural malignancy and that there are no radiologic features that can distinguish between the primary and secondary malignant pleural neoplasms that manifest with this finding.

A. Hodgkin’s disease may effect the pleura, but the typical manifestation on chest imaging is that of prevascular and paratracheal lymphadenopathy in a young patient with palpable cervical and/or supraclavicular lymph nodes. Calcifications are rare in pretreated Hodgkin’s disease.
B. Metastases to the pleura may produce circumferential nodular thickening. The most common primary neoplasm to produce this finding is adenocarcinoma of the lung. Leiomyosarcoma is a rare neoplasm unlikely to produce this finding and thus is not the best option.
C. While the soft tissue masses seen along the mediastinal pleura could represent mediastinal neurogenic neoplasms, the other lesions do not exhibit the typical features of chest wall neurogenic tumors, which typically produce benign pressure erosion and bilateral chest wall and mediastinal involvement.
D. The most likely diagnosis in this case is invasive thymoma with pleural implantation, given that the patient has a dominant anterior mediastinal mass. Most thymomas are encapsulated neoplasms, which manifest as unilateral lobular anterior mediastinal masses. One of the radiologist’s principal roles in evaluating these lesions is the exclusion of invasion into adjacent mediastinal fat, cardiovascular structures and/or lung. A well-documented manifestation of invasive thymoma is the presence of drop metastases to the ipsilateral pleura, which may grow to circumferentially encase the lung and mimic other malignant pleural neoplasms.
E. Pleural thickening from empyema is usually thin and smooth rather than circumferential and nodular. In addition, empyema is characterized by fluid in the pleural space separating the visceral and parietal pleurae. Patients with empyema usually have a history of prior pulmonary infection with parapneumonic pleural effusions that later form pleural abscesses and empyemas.

Findings: Moderate diffuse cardiomegaly has a globular or “water bottle” configuration and normal pulmonary vascularity. On the lateral radiograph, the classical retrosternal “fat pad sign” consists of two vertical linear lucencies, which sandwich an opaque stripe. This is the key radiographic finding.

A. Although diffuse cardiomegaly is compatible with a cardiomyopathy, the fat pad sign reflects a large pericardial effusion.
B. Aortic insufficiency can lead to left ventricular enlargement and cardiomegaly on chest radiography. The fat pad sign typically is not present in this condition.
C. Mitral insufficiency can cause left atrial and left ventricular enlargement. A pericardial effusion typically is not present.
D. The globular water bottle heart and the fat pad sign on the lateral radiograph make this the most likely choice. The lucent bands represent separation of the epicardial and mediastinal fat by the fluid-filled pericardium (opaque band).
E. Pericardial cysts typically manifest as right cardiophrenic angle masses.

Findings: There is consolidation with air bronchograms in the left lower lobe typical of acute lobar pneumonia.

A. Bacterial pneumonia is the most common lung infection in HIV-positive patients and is often caused by pneumococcus. The most common radiographic changes are lobar or segmental consolidation.
B. Pneumocystis pneumonia most often presents with diffuse, often perihilar reticular or granular opacities. Normal chest radiographs are not uncommon. Lobar consolidation is rare and not the first consideration in this patient.
C. Tuberculosis presents with the reactivation pattern (posterior segment upper lobe infiltration/ cavitation) in HIV patients with CD4 counts of more than 200 cells/cu mm and progressively more in the primary pattern (adenopathy, effusion, consolidation, and military disease) with CD4 counts of less than 200. Lobar consolidation is rare in HIV-positive patients without AIDS.
D. Histoplasma capsulatum is a fungus that is found in the United States along river valleys, particularly the Ohio and Mississippi. The radiographic manifestations are varied and include hilar adenopathy, patchy consolidation, solitary or multiple nodules, and miliary pattern. The radiographic manifestations and recent history of travel are not provided in this case.

A. Wegener’s granulomatosis is a multisystem disease that is characterized by the presence of necrotizing granulomatous inflammation involving the upper and lower respiratory tracts, glomerulonephritis and necrotizing vasculitis of the lungs. Clinical symptoms consist of cough, hemoptysis and dyspnea. The radiographic manifestations include nodules (with or without cavitation), airspace opacities and tracheal or bronchial thickening. Pericardial effusion is not a feature of this disease.

B. Perilymphatic opacities occur in relation to peribronchovascular interstitium, the interlobular septa, and the subpleural regions. Thus, they do not represent a tree-in-bud pattern on HRCT scans of the chest.
D. Tree-in-bud pattern on high-resolution CT (HRCT) scan of the chest represents dilated bronchioles that are impacted with mucus, fluid, or pus. Because of the branching pattern of the dilated bronchiole, its appearance has been likened to a budding tree or the children’s toy, jacks. On HRCT, tree-in-bud is usually seen few millimeters from the pleural surface as branching or nodular opacities. It may also appear as centrilobular opacities depending on the plane of the scan. The finding is indicative of small airways disease.

A. Blood eosinophilia is not necessary to make the diagnosis of eosinophilic lung disease. The term pulmonary eosinophilia, synonymous with pulmonary infiltration with eosinophilia, describes a group of diseases in which blood and/or tissue eosinophilia affects major airways and lung parenchyma.
B. Correct. Eosinophilic lung diseases are a group of pulmonary disorders that are characterized by abundant eosinophils in the pulmonary opacities. They are classified into groups with and without a specific cause. The specific causes include drugs, such as sulfonamides, parasites, and fungi.
C. Chronic eosinophilic pneumonia has classic radiographic and chest CT findings of peripheral, nonsegmental, homogenous alveolar opacities, often with air bronchograms.
D. Correct. Loffler’s syndrome is characterized by blood eosinophilia, absence of or mild symptoms and signs (cough, fever, and dyspnea), one or more nonsegmental mixed interstitial and alveolar pulmonary opacities that are transitory or migratory, and spontaneous clearing of the opacities.

"A. It is a necrotizing vasculitis that is characterized clinically by asthma, fever and eosinophilia. Radiographic manifestation includes bilateral patchy consolidations but not air-trapping.
B. It is an autoimmune disorder of unknown etiology that is characterized by repeated episodes of pulmonary hemorrhage. No air-trapping is noted.
C. Also known as congenital pulmonary venolobar syndrome. It is a congenital anomaly that consists of hypoplasia of the right lung and the right pulmonary artery. There is anomalous venous drainage of the right lung into the systemic venous system, usually below the diaphragm into the inferior vena cava. No air-trapping is noted.
D. The syndrome is believed to be initiated by a viral bronchiolitis in childhood. It is characterized by hyperlucent lobe or lung. The hyperlucency is due to bronchiolar obliteration and this results in air-trapping on expiratory CT scan.

Swyer-James AKA Brochiolitis Obliterans
Terminology
Concentric luminal narrowing of the membranous and respiratory bronchioles secondary to submucosal and peribronchiolar inflammation and fibrosis without intraluminal granulation tissue and polyps

Imaging Findings
Bronchiectasis common with post-infectious BO
Air trapping at expiratory HRCT
Inspiratory scans may be completely normal
Caveat: In patients with widespread disease, end-expiratory CT sections may appear virtually identical to inspiratory CT sections because air trapping extensive

C. Correct. Bronchogenic cysts are congenital lesions that result from an abnormality of budding of the tracheobronchial tree during embryologic development. They are most commonly found in the subcarinal location and thus there presence in this location will cause obliteration of the azygoesophageal interface. Azygoesophageal interface is formed by the interposition of the aerated lung and the lateral wall of the azygous vein and esophagus.

A, B and D. Incorrect. Anterior and Posterior junction lines are longitudinal opacities that are formed by the close apposition of the visceral and parietal layers of the pleura of both the lungs as they come together anteriorly and posteriorly to the mediastinum. Descending aortic interface is formed by the juxtaposition of the aerated lung and the soft tissue of the left lateral margin of the descending thoracic aorta.

A. Very common in the later stages of asbestosis.
B. Upper lung nodules are typical of silicosis and granulomatous disease, not asbestosis.
C. This is the most common early manifestation of asbestosis and is best demonstrated by high resolution CT. With time, these progress to a coarse reticular pattern.
D. Correct. Pleural plaques and pleural effusions are common findings in asbestosis.

A. In Langerhans cell histiocytosis. The cysts are often irregular and seen in the upper lobes.
B. Correct. In early centrilobular emphysema the cystic areas within the lung have an imperceptible wall. In later stages, the entire secondary lobule, except the lobular wall is destroyed and can appear as multiple adjacent polygonal cysts.
C. The disease is in the lower lobes.
D. The cysts are smooth and round and they are evenly distributed throughout the lungs.

A. Thymomas may be cystic but should have a component that enhances following gadolinium administration.
B. Germ cell tumors can also be cystic but they tend to be septated with enhancing septations. They may contain fat or calcium.
C. This is the correct answer. It is shaped like the thymus and has the properties of a benign cyst (low-attenuation on CT) and on MRI (no enhancement).
D. Most lymphomas are solid but when they are cystic, the cysts only represent a fraction of the lesion. In this case, the cyst is the dominant, if not the whole lesion.

A. Correct.
B. Correct.
C. Pleural metastases may be focal and nodular but are more frequently associated with pleural effusion or diffuse pleural thickening. High density calcified pleural metastases (e.g. from osteogenic sarcoma) are extremely rare.
D. Sequelae of tuberculous pleuritis range from minimal pleural thickening to severe thickening encasing the lung often with calcification. On CT the pleural thickening is usually smooth and the calcification is linear and confined to the visceral pleura.

A. The filling defect in the left main pulmonary artery does not have the features of acute pulmonary embolism, i.e. it is eccentric rather than central and is not surrounded by contrast material. The presence of bronchial artery collaterals suggests a chronic process, which partially obstructs the pulmonary arterial vasculature.
B. Malignant tumors within the central pulmonary arteries usually demonstrate contrast enhancement and frequently extend beyond the margins of the artery. The bronchial artery collateral supply also suggests a long standing processes.
C. The filling defect in the left pulmonary artery displays typical features of a chronic pulmonary embolus. There is a peripheral filling defect at an obtuse angle with the vessel wall with multiple collateral bronchial arteries in the mediastinum.
D. Although the pulmonary artery is dilated indicating pulmonary arterial hypertension, the presence of chronic embolus excludes the diagnosis.

"Findings: Chest radiograph demonstrates a collapsed right upper lobe and a right suprahilar mass. The minor fissure is elevated and is concave peripherally. However, it has a convex border medially caused by a tumor mass in the right hilum. The shape of the fissure resembles a ""S"" shape. This appearance is referred to as the ""S"" sign of Golden. Note the elevation of the right hemidiaphragm, another sign of volume loss.

"Findings: Chest radiographs show bilateral symmetric alveolar opacites. CT demonstrates bilateral ground glass opacity with superimposed thickened septal lines, creating the so-called “crazy-paving” appearance.

Findings: The chest radiograph shows a subcarinal mass. The CT study demonstrates a round structure with a homogeneous fluid-attenuation in the subcarinal location.

Findings: The chest radiograph shows localized pleural thickening. CT examination reveals a thickened, enhancing “split-pleura” sign with gas in the pleural space. The different dimensions in the right-left direction as compared to the anteroposterior dimension confirm the pleural nature. Parenchymal lesions are spherical and so are equal in length in these 2 dimensions.

Findings: CT findings include a well-defined nodule containing fat and popcorn calcification, indicating a chondroid matrix.

Findings: The chest and CT show symmetric bilateral hilar enlargement consistent with lymphadenopathy. Subcarinal nodes and splenic lesions are also seen on the CT.

Findings: Bilateral peripherally based cavitary nodules and nodular-like opacities with bilateral pleural effusions and a vegetation on the tricuspid valve.

A. Tuberculosis (TB) usually presents as an upper lobe cavitary infiltrate. If anything, this process was more predominant in the lower lobes. In addition, this process was peripheral, a feature that has not been described with TB. Also, TB would not explain the tricuspid vegetation.
B. The key to the diagnosis of septic emboli is the identification of bilateral, peripheral opacities with cavitation. When combined with the patient's young age and the history of fevers, septic emboli become a favored diagnosis. The visualization of the vegetation on the tricuspid valve clinches the diagnosis. Usually, the source of the septic emboli is from a venous catheter, an infected valve, or a peripheral septic thrombophlebitis (as in Lemierre's syndrome). In this case, the patient was an intravenous drug user who had acquired tricuspid endocarditis.
C. Though the patient's age and the cavitary nodules and nodular opacities would be good for metastatic cervical cancer, this answer is incorrect. Like septic emboli, metastatic disease may present with a lower lobe predominance and identification of vessels leading to the nodules (feeding vessel sign). However, the metastatic disease would not explain the fever and the vegetation on the tricuspid valve.
D. Cryptogenic organizing pneumonia (COP, or BOOP, as it is also called) may present with fevers and peripheral opacities. However, cavitation would be unusual, as would be pleural effusions. COP would not explain the tricuspid vegetation.
E. Wegener's granulomatosis may present with cavitary bilateral nodules and pleural effusions with a history of fever. Like the other incorrect answers, however, Wegener's would not explain the tricuspid vegetation.

Findings: A well-defined area of ground glass attenuation in the right upper lobe with normal surrounding parenchyma (notably no emphysema).

A. Squamous cell carcinomas tend to be central and close to the bronchi. When peripheral, they may cavitate. Associated postobstructive change is usually found. Ground glass is not a feature that has been described with squamous cell carcinoma.
B. Metastatic disease to the lung tends to be multiple and more pronounced in the lower lungs. Patients with nonbronchogenic adenocarcinomas and sarcomas may present with isolated metastasis. These tend to be smooth soft-tissue attenuation nodules, not ground glass. Rarely, angioinvasive tumors (such as angiosarcomas) may have a halo around a solid nodule. The single ground glass opacity presented here would be unusual for metastatic disease.
C. Peripheral ground glass opacity (GGO) has become a well-recognized appearance of pulmonary neoplasms. By far, the most common pulmonary cancer to have this appearance is bronchioloalveolar carcinoma (BAC), a subtype of bronchogenic adenocarcinoma. This pattern has also been seen with localized non-BAC adenocarcinomas. It is because of its tendency to grow along the interstitium without invasion (lepidic growth pattern) that many feel BAC has this appearance. BAC may not be associated with smoking, and its incidence is on the rise. It is important to know about this pattern because of potential confusion with pneumonia on screening lung CT.
D. Carcinoid tumors are usually central and associated with a bronchus. When peripheral, they tend to be solid and lobulated. They may enhance with intravenous contrast. Ground glass has not been reported with carcinoid tumors.
E. Large cell tumors tend to present as solid peripheral masses that actually may be large in size. Ground glass would be an unusual CT appearance for these tumors.