A 28-year-old woman has dry cough, dyspnea, uveitis, and tender shin nodules. Chest radiograph shows bilateral hilar lymphadenopathy with clear lung fields. Transbronchial biopsy shows non-necrotizing granulomas containing star-shaped cytoplasmic inclusions. Which laboratory abnormality is expected?
- A Hypercalciuria due to extrarenal 1-alpha hydroxylase activity in granulomas ✓
- B Positive c-ANCA against proteinase 3
- C Reduced CD4 to CD8 ratio in bronchoalveolar lavage fluid
- D Low serum angiotensin converting enzyme level
Correct answer: A. Hypercalciuria due to extrarenal 1-alpha hydroxylase activity in granulomas
Explanation
Sarcoidosis granulomas express 1-alpha hydroxylase, converting 25-hydroxyvitamin D to active calcitriol, causing hypercalcemia and hypercalciuria. Asteroid bodies and Schaumann bodies support the diagnosis but are not specific. Serum ACE is typically elevated, BAL shows an increased CD4 to CD8 ratio reflecting helper T cell expansion, and c-ANCA points to granulomatosis with polyangiitis rather than sarcoidosis.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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