Described is a case of a female patient with a rare sporotrichoid form of dermal infection due to Mycobacterium marinum acquired through the contact with aquarium water. The focus on the forearm was excised by plastic surgeon and histological examination revealed an epitheloid granuloma with central necrotic suppuration; staining for mycobacteria gave a negative result. Diagnosis was made by cultivation of the excised tissue on solid media and subsequent identification using microscopic methods. On last revision, eight months after therapeutic excision, the dermal manifestation of the infection was healed.

        Key words: Mycobacterium marinum - dermal infection - clinical picture - differential diagnosis - therapy