Pulmonary mucormycosis.

Mucormycosis is an opportunistic, angioinvasive fungal infection characteristically affecting individuals with diabetes mellitus, chronic renal failure, and hematologic malignancies. In most cases it is a rapidly progressive infection with an 80% overall mortality. Radiographic manifestations are usually nonspecific focal consolidation or masses. The air crescent sign is a rare manifestation of angioinvasive fungi and indicates either aspergillosis or mucormycosis.