Mucor infection: difficult diagnosis.

Mucormycosis is a rare, highly aggressive and usually fatal infection, which affects immunocompromised patients. This case report describes a patient with acute promyelocytic leukemia who received antifungal therapy for a suspected pulmonary Aspergillus infection. Material from a lobectomy suggested that on histologic grounds the diagnosis had to be changed to mucormycosis. High suspicion of a Mucor infection favors early detection and timely appropriate antifungal therapy, which is crucial for the prognosis of these patients.