Breakthrough Penile Mucormycosis in a Patient With Acute Myelogenous Leukemia on Posaconazole Prophylaxis

In patients with acute myelogenous leukemia, posaconazole prophylaxis has been shown to prevent deep invasive fungal infections, including mucormycosis. In the present case, posaconazole prophylaxis was initiated in a 58-year-old man undergoing induction chemotherapy for acute myelogenous leukemia. Three weeks after initiating chemotherapy, he developed a tender violaceous macule on the shaft of his penis. The initial differential included fixed drug eruption versus pyoderma gangrenosum. However, punch biopsy ultimately showed mucormycosis, and cultures grew Rhizopus species, despite therapeutic posaconazole trough. He was treated with intravenous amphotericin B and required right orchiectomy, penectomy, and hyperbaric oxygen therapy. Oral posaconazole was reinstituted after completion of amphotericin B course, and at 4 months follow-up, his penectomy site was fully healed. As demonstrated by the present case, not all mucormycoses are prevented by posaconazole prophylaxis. A high index of suspicion and early biopsy for prompt diagnosis are of critical importance in improving outcomes.