[Mycobacterium malmoense cutaneous infection in an immunocompetent patient]

Mycobacterium malmoense is a mycobacterium rarely described as a human pathogen. We report the first case of cutaneous infection in an immunocompetent patient.

A 75-year-old woman presented with a cutaneous nodula on the back of her left hand. Histology of the node biopsy showed non caseating granuloma with giant and epithelioid cells. Acid-fast bacilli were isolated at direct smear and after culture. Mycobacterium malmoense was identified. The lesion has healed after surgery.

Mycobacterium malmoense is an environmental mycobacterium isolated from soil and water. Typically, most patients with Mycobacterium malmoense infections are old people with previously lung disease. A few cervical lymphadenitis in children and rare cases of tenosynovitis of the hand have been reported. Disseminated infections with cutaneous lesions have been exceptionally described in immunocompromised patients. Mycobacterium malmoense is slow growing and its identification is hard, sometimes requiring molecular analysis. Probably it's the reason why we present the first description of a cutaneous infection in an immunocompetent patient. This case indicates that Mycobacterium malmoense is also a cutaneous pathogen.