VARIED RADIOLOGIC APPEARANCES OF PULMONARY ASPERGILLOSIS

Pulmonary aspergillosis represents a common, potentially lethal opport unistic infection that has four unique forms: allergic bronchopulmonar y aspergillosis (ABPA), aspergilloma, and invasive and semi-invasive a spergillosis. In individuals who are at risk, pulmonary aspergillosis is characterized by a spectrum of clinical and radiographic findings t hat are intrinsically related to the status of the immune system or th e presence of structural lung disease. ABPA, occurring almost exclusiv ely in asthma patients, is characterized radiographically by fleeting pulmonary alveolar opacities caused by deposition of immune complexes and inflammatory cells within the lung parenchyma. Mucus plugging and bronchial wall thickening can be expected in time. Aspergilloma, occur ring in patients with structural lung disease, typically appears radio graphically as a focal intracavitary mass and is characterized initial ly by an increase in the wall thickness of a preexisting cavity or cys t. Invasive aspergillosis, which occurs primarily in profoundly immuno compromised patients, may exhibit nonspecific patchy nodular opacities or lobar-type air-space disease in cases with vascular invasion. Comp uted tomography may reveal a halo or ground-glass attenuation and is m ore accurate in the detection of early disease. Cavitation often devel ops with time and typically results in the air crescent sign. Semi-inv asive aspergillosis is radiographically similar to the invasive form b ut differs in clinical course, being associated with mild immunosuppre ssion or chronic illness and typically progressing over the course of months rather than weeks.