Unmasking tuberculous arthritis in a prosthetic joint: Diagnostic and therapeutic challenges.

An 85-year-old woman with a history of total knee replacements for osteoarthritis in the past, presented with left knee swelling and pain that persisted for 14 months. An initial diagnosis of synovial cyst was made, and she underwent multiple aspirations and symptomatic treatments without improvement. Repeat arthrocentesis showed a WBC of 56,000/μL with 61 % neutrophils and 34 % lymphocytes.