The clinicopathological spectrum of non-tuberculous mycobacterial osteoarticular infections.

We studied the clinicopathological features of eight patients in whom a non-tuberculous mycobacterium was unexpectedly isolated from osteoarticular material obtained at operation. Three distinct types of infection with non-tuberculous mycobacteria were found: tenosynovitis, synovitis, and osteomyelitis. Tissue specimens from these sites showed a spectrum of pathological findings, including (1) virtually no inflammation, (2) mild to severe non-specific chronic inflammation, (3) granulomas without necrosis, and (4) caseating epithelioid granulomas that were indistinguishable from those of tuberculosis. In six patients the infection responded well to adequate surgical excision alone. In the remaining two the infection responded to surgical intervention and antituberculous therapy.