A Fishy Situation: Hand Infection due to Mycobacterium marinum Mistaken for Giant Cell Tumor.

Mycobacterium marinum is an acid-fast bacterium (AFB) associated with exposure to water and aquatic species. When inoculated, infection can result in nodular cutaneous lesions. In the absence of detailed history or culture data, these nodular skin lesions can be mistaken for noninfectious orthopedic conditions. We present a case of M. marinum mistaken for a giant cell tumor. This case illustrates the overlap in these conditions, as well as the utility of QuantiFERON Gold testing to provide supportive evidence for the diagnosis of Mycobacterium marinum.