A 40-year-old man with pulmonary tuberculosis develops severe headache, neck stiffness, and cranial nerve palsies over 5 days. CSF analysis shows: protein 200 mg/dL, glucose 25 mg/dL (simultaneous blood glucose 110 mg/dL), and 500 cells/μL with lymphocyte predominance. Which finding is most characteristic on basal meningeal biopsy?

• A Non-caseating granulomas with Langhans giant cells
• B Fibrinoid necrosis of vessel walls with neutrophilic infiltrate
• C Caseating granulomas with acid-fast bacilli ✓
• D Foamy macrophages containing encapsulated yeast forms

Explanation

Tuberculous meningitis shows caseating granulomas with Langhans giant cells and acid-fast bacilli (Mycobacterium tuberculosis) in the basal meninges. CSF classically shows very high protein, low glucose, and lymphocytic pleocytosis. Non-caseating granulomas are seen in sarcoidosis. Fibrinoid necrosis with neutrophils suggests vasculitis. Encapsulated yeast in macrophages suggests cryptococcal meningitis.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.