A review of zygomycosis due to Basidiobolus ranarum

Zygomycosis due to Basidiobolus ranarum (entomophthoromycosis basidiobolae, subcutaneous zygomycosis, subcutaneous phycomycosis, basidiobolomycosis) is a granulomatous infection of the skin and subcutaneous tissues characterized by the formation of fluctuant firm and non-tender swellings, generally on the extremities, trunk and rarely other parts of the body. The causative agent is common in soil, decaying vegetable matter, and the gastrointestinal tracts of amphibians, reptiles, fish and bats. It is presumed that infection is acquired through exposure to B. ranarum following minor trauma to skin or insect bites. The disease usually occurs in children, less often in adolescents and rarely in adults. Males are much more frequently affected than females. Laboratory diagnosis is based on histopathology and culture. The typical histopathological feature is the presence of thin-walled, broad often aseptate hyphae or hyphal fragments with an eosinophilic sheath, frequently phagocytized within giant cells. Basidiobolus ranarum is known to produce several enzymes, e.g. lipase and protease that probably play roles in the pathogenesis of infections caused by this mould. An immunological test has been developed for specific diagnosis of the disease. Though potassium iodide (KI) has been the traditional drug employed in the treatment of infections by B. ranarum, several other drugs, viz amphotericin B, cotrimoxazole, ketoconazole, itraconazole and fluconazole have been successfully tried.