Fish, flesh and a good red herring: a case of ascending upper limb infection in a renal transplant patient.

While newly developed potent immunosuppressive agents have dramatically reduced the incidence of rejection of transplanted organs, they have increased the patients' susceptibility to opportunistic infections and cancer. Here we report a rare skin infection caused by atypical mycobacterium marinum in a 50-year-old female renal transplant recipient. The patient presented with localized skin lesion on the dorsum of her hand, which was misdiagnosed as gout. Only after the lesions spread in a sporotrichoid pattern, a cutaneous infection with atypical mycobacteria was suspected. The diagnosis was based on histopathological analysis as well as mycobacterial culture, both showing infection with atypical mycobacterium. Three months of antimycobacterial treatment led to a marked regression of the lesions. Sporotrichoid lesions in renal transplant patients are rare and a diagnostic challenge for the physician. A thorough history and a low threshold for skin biopsies could prevent painful and unnecessary surgical interventions.