Disseminated cutaneous infection with Mycobacterium chelonae in a patient with steroid-dependent rheumatoid arthritis

Mycobacterium chelonae is a rapidly growing atypical mycobacterium that is a normal commensal of water and soil. We report a case of a 61-year-old man with seronegative rheumatoid arthritis and fibrosing alveolitis on long-term prednisolone who presented with a number of tender, red, subcutaneous nodules on his upper arms and a pustule on his left cheek. Histopathologic examination revealed dense neutrophilic collections within the deep dermis and subcutaneous fat with abscess formation. Long filamentous organisms were seen within these collections and were subsequently identified by special stains and PCR as Mycobacterium chelonae. Treatment was not possible as the patient developed bacteria bronchopneumonia before identification of the organism and he subsequently died. Post-mortem revealed no extra-cutaneous evidence of mycobacterium infection.