A 29-year-old woman has dry cough and dyspnea for 4 months. CXR shows symmetric bilateral hilar lymphadenopathy. HRCT shows perilymphatic micronodules along fissures. Transbronchial biopsy shows non-caseating granulomas. Serum calcium is 11.2 mg/dL. Which finding best supports sarcoidosis over tuberculosis as the cause?

• A Non-caseating granulomas on histology
• B Elevated serum calcium
• C Dry cough of 4 months duration
• D Symmetric bilateral hilar adenopathy ✓

Explanation

Symmetric bilateral hilar lymphadenopathy is the hallmark radiographic feature of sarcoidosis (stage I disease); tuberculous nodes are characteristically unilateral or asymmetric. Non-caseating granulomas occur in both conditions and in berylliosis, so histology alone cannot discriminate. Hypercalcemia from granuloma-derived calcitriol occurs in both diseases. Indian exam convention stresses that caseation must be actively sought before labeling granulomas as sarcoidal.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

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