A 26-year-old woman has chronic monoarthritis of the left knee for five months with low grade fever and raised ESR. Synovial fluid analysis shows lymphocytic predominance and culture for pyogenic organisms is sterile. Which investigation will provide the most definitive confirmation of tuberculous arthritis?

• A Strongly positive Mantoux test
• B Serial radiographs demonstrating juxta articular osteoporosis
• C Histopathology of synovial biopsy showing caseating epithelioid granulomas with Langhans giant cells ✓
• D Markedly elevated serum CRP

Explanation

Definitive diagnosis rests on demonstrating the organism or its characteristic histology. Synovial biopsy showing caseating epithelioid granulomas with Langhans giant cells, ideally supported by acid fast staining or mycobacterial culture of the tissue, is confirmatory. A positive Mantoux merely reflects prior sensitization and is common in endemic populations, so it cannot establish joint infection, and osteoporosis with raised CRP are nonspecific inflammatory markers.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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