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ESSENTIALS OF DIAGNOSIS
Symptoms related to the lung, skin, eyes, peripheral nerves, liver, kidney, heart, and other tissues.
Demonstration of noncaseating granulomas in a biopsy specimen.
Exclusion of other granulomatous disorders.
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GENERAL CONSIDERATIONS
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Sarcoidosis is a systemic disease of unknown etiology characterized in about 90% of patients by granulomatous inflammation of the lung. The incidence is highest in North American Blacks and northern European Whites; among Blacks, women are more frequently affected than men. Onset of disease is usually in the third or fourth decade.
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A. Symptoms and Signs
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Patients may have malaise, fever, and dyspnea of insidious onset. Symptoms caused by skin involvement (erythema nodosum, lupus pernio [Figure 9–6]), iritis, peripheral neuropathy, arthritis (Chapter 20), or cardiomyopathy may also prompt the patient to seek care. Some individuals are asymptomatic and come to medical attention after abnormal findings on chest radiographs (typically bilateral hilar and right paratracheal lymphadenopathy). Physical findings are atypical of interstitial lung disease in that crackles are uncommon on chest examination. Other symptoms and findings may include parotid gland enlargement, hepatosplenomegaly, and lymphadenopathy.
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B. Laboratory Findings
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Laboratory tests may show leukopenia, an elevated erythrocyte sedimentation rate, and hypercalcemia (about 5% of patients) or hypercalciuria (20%). Angiotensin-converting enzyme (ACE) levels are elevated in 40–80% of patients with active disease. This finding is neither sensitive nor specific enough to have diagnostic significance. Physiologic testing may reveal evidence of airflow obstruction, but restrictive changes with decreased lung volumes and diffusing capacity are more common. Skin test anergy is present in 70%. ECG may show conduction disturbances and dysrhythmias.
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Radiographic findings are variable and include bilateral hilar adenopathy alone (radiographic stage I), hilar adenopathy and parenchymal involvement (radiographic stage II), or parenchymal involvement alone (radiographic stage III). Parenchymal involvement is usually manifested radiographically by diffuse reticular infiltrates, but focal infiltrates, acinar shadows, nodules, and, rarely, cavitation may be seen. Pleural effusion is noted in less than 10% of patients. Stage IV disease refers to advanced fibrotic changes principally in the upper lobes.
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D. Special Examinations
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The diagnosis of sarcoidosis generally requires histologic demonstration of noncaseating granulomas in biopsies from a patient with other typical associated manifestations. Other granulomatous diseases (eg, berylliosis, tuberculosis, fungal infections) and lymphoma must be excluded. Biopsy of easily accessible sites (eg, palpable lymph nodes, skin lesions, or salivary glands) is likely to be positive. Transbronchial lung ...