Sporotrichoid Mycobacterium marinum infection of the face following a cat scratch

Mycobacterium marinum infections in humans uncommonly affect the face and are not known to be associated with cat scratches. We describe a 24-year-old woman who presented with a 3-month history of multiple tender, occasionally discharging cystic nodules involving the left side of her face in a sporotrichoid distribution. She had suffered a cat scratch to her left lower eyelid 3 weeks before the onset of the eruption and owned multiple tropical fish tanks. She was systemically well and had no lymphadenopathy. She had a background history of a 4.5-mm-thick nodular melanoma of her temple treated by wide local excision and negative sentinel lymph node biopsy 4 years prior. Skin biopsies showed multiple variably sized granulomas surrounded by thick cuffs of lymphocytes involving the superficial and deep dermis with no organisms seen on Ziehl-Neelsen, peroidic acid-Schiff and methenamine silver stains. Laboratory investigations showed a mildly raised erythrocyte sedimentation rate but normal full blood count and C-reactive protein. Fluid from the left cheek grew an acid-fast bacillus identified as Mycobacterium marinum. The skin eruption cleared after 5-month treatment with oral clarithromycin 500 mg twice daily and rifampicin 600 mg daily.