A bilateral upper zone interstitial pattern is seen with hilar and paratracheal adenopathy. Lung volumes are normal. Cardiac size is normal. The physical signs are inconsistent with an infectious process. The CXR shows hilar, paratracheal LN, and parenchymal disease. Sarcoidosis may be associated with uveitis, skin lesions, bony cysts, and hypercalcemia, which is due to abnormal vitamin D metabolism. Sarcoidosis is a systemic disease of unknown etiology characterized pathologically by widespread development of noncaseating epithelioid cell granulomas, which may resolve or conve to fibrous tissue. The disease most commonly affects hilar lymph nodes and lungs, but uveitis and involvement of other organs such as the liver, spleen, skin, bone, and salivary glands are not rare. Lab studies may show anemia, leukopoenia, elevated SED rates, blood eosinophilia, hypercalcemia, hypercalciuria, and elevated levels of serum angiotensin-conveing enzymes. Half of the cases are detected incidentally on chest radiograph. Patients with adenopathy alone are usually asymptomatic, althoughpatients with pulmonary involvement may experience weight loss, fatigue, fever, cough, or shoness of breath. Hemoptysis is rare unless it is associated with end-stage sarcoidosis and a superimposed mycetoma. The disease is most common in African Americans, Pueo Ricans, and West Indians. Women are more susceptible than men. Diagnosis is usually confirmed by transbronchial biopsy, which can demonstrate granulomas despite the absence of radiographic evidence of this peribronchial disease. Adenopathy is the most common manifestation. Symmetrical, hilar, and classically right paratracheal involvement is seen. Unilateral hilar adenopathy is seen in less than 5% of cases. Peripheral "eggshell" lymph node calcification is occasionally seen. Pleural effusion is rare. Radiographic staging of sarcoid is as follows: Stage 0: normal finding, 10% at presentation, with the primary problem being nonpulmonary Stage 1: adenopathy without pulmonary disease, 50% at presentation Stage 2: adenopathy with pulmonary disease, 30% at presentation Stage 3: pulmonary disease without adenopathy, 10% at presentation Stage 4: pulmonary fibrosis, usually as a sequel to stage 3, rare at presentation Stage 1 disease resolves within a few years in most patients, and less than one-third of patients with stage I disease develop lung disease. Adenopathy is usually present when there is pulmonary disease. The lung involvement results from deposition of noncaseating granulomas along the lymphatic lining of the bronchial vascular bundles and interlobular septa. Findings include small, irregular interstitial and subpleural nodules throughout the lungs. Confluent interstitial infiltrates may be asymmetric, and cavitation is rare. The midzone and upper zone are most commonly involved, whereas the lung periphery and the bases are generally spared. Pulmonary involvement usually resolves but does progress to fibrosis in less than 20% of the cases, with architectural distoion, traction, and pleural thickening. The distribution is often patchy, in contrast to the peripheral lower lobe distribution of IPF. Occasionally, pulmonary sarcoidosis may appear as ground-glass opacities, patchy consolidation, or rounded "cannonball" infiltrates described as alveolar sarcoid.