Histology of early lesions of AIDS-associated Kaposi's sarcoma.

The original cutaneous biopsy specimens of 93 patients who presented themselves to the Memorial Sloan-Kettering Cancer Center with acquired immunodeficiency syndrome (AIDS)-related Kaposi's sarcoma (KS) were systematically reviewed for 23 histologic variables. KS was the initial manifestation of AIDS in all of the patients. The vast majority of patients presented with plaque histology of KS. Early lesions of KS were characterized by the presence of dilated vascular spaces haphazardly arranged in the biopsy specimen, a sparse inflammatory cell infiltrate composed of lymphocytes (usually without plasma cells), and aggregates of cuboidal cells with the appearance of epithelioid cells. Individually necrotic tumor cells were present in nearly every case. Spindle cells arranged in fascicles or nodules were seen in a minority of cases. These data provide an overview of the different histologic patterns seen in initial lesions of AIDS-associated KS and may lead to better understanding of the pathogenesis of this tumor.