Mycobacterium tuberculosis infection of a tophaceous pseudogout nodule.

Musculoskeletal infections are uncommon complications of monosodium urate and calcium pyrophosphate dihydrate (CPPD) crystal deposition disease, and frequently involve gram positive and negative organisms. Tumoral calcinosis (tophaceous pseudogout) is a rare manifestation of CPPD deposition disease. We describe a highly unusual case of an infection by Mycobacterium tuberculosis (TB) of a tophaceous pseudogout nodule in a patient with endstage renal disease. The highly destructive nature of this case of combined CPPD arthropathy and musculoskeletal TB underscores the urgency of diagnosing this infection in susceptible patients from countries with high prevalence rates of TB infection.