Radiologic-Pathologic Correlation of the CT Halo Sign in Invasive Pulmonary Aspergillosis

Invasive pulmonary aspergillosis in the immunocompromised host is difficult to diagnose. Early therapy with amphotericin B improves survival. We correlated early pathologic findings with high-resolution CT of a fixed-inflated air-dried lung obtained from an autopsied patient with invasive pulmonary aspergillosis. Two distinct types of lesions were found radiologically. A large zone of air space consolidation was shown to be a confluent bronchopneumonia, and small halo-like lesions were shown to correspond to a central fungal nodule surrounded by a rim of coagulative necrosis. The halo lesion may represent an early specific sign by which invasive pulmonary aspergillosis can be diagnosed.