Rapidly progressive cutaneous Rhizopus microsporus infection presenting as Fournier's gangrene in a patient with acute myelogenous leukemia.

Zygomycetes are ubiquitous in nature and can cause fulminant infections in the immunocompromised host. Known risk factors include hematologic malignancy, neutropenia, diabetes mellitus, steroid use, and trauma (1). A recent increase in the incidence of zygomycosis compared with candidiasis or aspergillosis may be explained by increasing use of antifungal agents lacking activity against Zygomycetes, in addition to the increasing numbers of higher risk bone marrow transplants (2). Organisms in the genus Rhizopus cause the majority of human infections. They typically manifest as cutaneous, rhino-cerebral, pulmonary, or gastrointestinal infection and may progress to disseminated disease. Cutaneous disease may arise either from direct inoculation of the skin, or less commonly, from hematogenous dissemination. Genital infection is exceedingly uncommon and only 4 cases involving the penis have been reported in the medical literature (3–6). Our case illustrates the diagnostic challenge of penile infection caused by Rhizopus. One of the key diagnostic dilemmas is that the appearance of skin lesions secondary to Rhizopus may be confused with viral eruptions, cutaneous leukemia, and bacterial necrotizing infection. The anatomy, physiology, and lymphatic drainage of the penis and perineum may predispose to rapid dissemination into the deep tissues of the pelvis with nearly universally fatal results. Current management strategies including novel adjuvant therapies are discussed.