Histoplasmosis presenting as the carpal tunnel syndrome

An otherwise asymptomatic 53 year old woman presented with symptoms typical of median nerve compression in the carpal tunnel. At operation, the tendon sheath was obviously inflamed. The diagnosis of histoplasmosis was made on microscopic examination of the surgical specimen. Cultures of synovial tissue grew H. capsulatum. Review of the literature and of experience at Barnes Hospital indicates that the carpal tunnel syndrome is a very unusual primary manifestation of histoplasmosis. However, as histoplasmosis is a treatable cause of the carpal tunnel syndrome, this diagnosis should be considered in endemic areas.