Pulmonary aspergillosis: pathologic and pathogenetic features.

Pulmonary aspergillosis is a relatively common fungal infection in individuals who are immunocompromised or have intrinsic lung disease. Clinical, radiological, and pathologic manifestations are quite varied and depend to a large extent on the type and severity of local or systemic host defense abnormalities. In individuals with only structural lung damage, saprophytic growth alone is the rule. Patients with atopy or other hypersensitivity state typically develop allergic disease, most often allergic bronchopulmonary aspergillosis. Individuals with other immunologic abnormalities, particularly immunodeficiency, and with granulocytopenia characteristically develop invasive disease, which may take several morphological forms. Identification of Aspergillus as the cause of all these disease variants is usually not a problem. However, recognition of the different patterns of disease is useful in understanding the pathogenesis of disease and in interpreting premortem clinical and radiographic abnormalities.