Histopathology of cryptococcosis and other fungal infections in patients with acquired immunodeficiency syndrome.

OBJECTIVE

To gain insight into the histopathologic characteristics of fungal infection in acquired immunodeficiency syndrome (AIDS).

METHODS

A review was conducted of the histopathology for 162 patients with evident fungal infection.

RESULTS

The microscopic appearance of esophageal candidiasis that was common in patients with single organ involvement revealed necrotic debris containing proliferating hyphae at the site of mucosal erosions without fungal invasion of underlying tissue. The incidence of oral and esophageal candidiasis was followed by that of pulmonary aspergillosis and Candida infection. Eighteen patients had generalized cryptococcosis, representing the commonest generalized fungal disease. The essential histologic features of the disease consisted of yeast cell proliferation with a histiocytic response, but only minor lymphocytic and neutrophilic components. This was different from the manifestations of both Candida and Aspergillus infections. The two histologic patterns recognized in the pulmonary cryptococcal lesions could be graded with respect to the degree and type of inflammatory reaction. The milder one consisted of small scattered foci of intra-alveolar cryptococcal proliferation with a histiocytic response. Another pattern involved massive cryptococcal infection, which might be simply more extensive than that in the former. Capillary involvement of alveolar septa was an important common finding in all 18 patients.