Histopathologic spectrum of oral Kaposi's sarcoma.

There has been a striking increase in the incidence of oral Kaposi's sarcoma in association with acquired immunodeficiency syndrome (AIDS). Oral lesions are seen in approximately 50% of AIDS patients with Kaposi's sarcoma. Lesions may appear as a flat or raised pigmented area, often resembling a benign vascular lesion, and are commonly found on the palate. Useful histopathologic criteria for the recognition and diagnosis of oral Kaposi's sarcoma include (1) atypical vascular channels (especially in early lesions), (2) a prominent spindle cell component in later lesions, (3) extravasated red blood cells, (4) hemosiderin, (5) the presence of eosinophilic bodies, (6) chronic inflammatory cells in early lesions, and (7) mitotic figures in tumor-stage lesions.