Epidemiology of Kaposi sarcoma: review and description of the nonepidemic variant.

Kaposi sarcoma (KS) is a rare angioproliferative tumor whose etiology is associated with human herpesvirus 8 (HHV 8). KS lesions typically involve the skin or mucosal surfaces and are characterized by purplish, red-blue, or brown-black macules, papules, and nodules which are prone to bleeding and ulceration. Definitive diagnosis requires biopsy revealing characteristic angioproliferative features. There are four widely recognized types of KS, which are histologically indistinguishable but differ in epidemiology and prognosis. These include classic, endemic, iatrogenic, and epidemic. KS has been increasingly recognized in a new subgroup of patients: men who have sex with men (MSM) but who are HIV-seronegative human immuodeficiency virus-seronegative and have no identifiable immunodeficiency. This fifth variant of KS, termed nonepidemic KS, resembles classic KS in presentation and prognosis. In this literature review, we report the characteristics of nonepidemic KS based on all published cases and highlight the need for clinicians to recognize this new clinical variant.