Isolated tuberculous osteomyelitis of the wrist: A case report

Extrapulmonary tuberculosis is an infection by <i>Mycobacterium tuberculosis</i> (MTB) involving any organ besides the lungs. Rarely, tuberculosis (TB) can infect the bones and joints, which accounts for only 1%-5% of total TB cases in Europe and the United States. In this case report, we present a 29-year-old man with history of gout who presented with chronic left wrist pain. Imaging demonstrated synovitis and erosive arthritis of the distal radius, ulna, and carpal bones. An initial synovial biopsy showed granulomatous inflammation but mycobacteria were not detected by microscopic examination or broad-spectrum polymerase chain reaction (PCR). Seven months later, a repeat bone biopsy showed TB osteomyelitis. The patient was then treated with anti-tuberculous therapy. Notably, imaging findings included the "penumbra sign," a highly specific feature seen on magnetic resonance imaging for subacute osteomyelitis. This case illustrates the challenges in diagnosing extrapulmonary TB osteomyelitis.