Mucormycosis is caused by fungi of the order Mucorales, most commonly Rhizopus oryzae; despite the name of the disease, Mucor species are only rarely the cause.

• Mucorales have characteristic wide (≥6- to 30-µm), thick-walled, ribbon-like, aseptate hyphal elements that branch at right angles.
• These ubiquitous environmental fungi primarily affect pts with diabetes, solid organ or hematopoietic stem cell transplants, prolonged neutropenia, malignancy, and deferoxamine treatment for iron overload syndromes.