(BMJ) - A 40-yo man presented w/ a lesion on his nose 1 wk after cutting it while swimming in a pool. It began as a pustule and progressed to an inflammatory nodule. Biopsy showed caseating granulomata. What is the diagnosis?
Histoplasmosis
Epidermal cyst
Mycobacterium marinum
Schistosomiasis
Foreign body reaction
You are correct. Swimming pool granulomata are caused by Mycobacterium marinum, an organism that can be resistant to chlorine in pools. Inoculation into damaged skin is required. The patient responded well to high-dose doxycycline.