Abstract

Kaposi's sarcoma (KS) has a place in the cultural zeitgeist as a herald of acquired immune deficiency syndrome (AIDS). However, KS had been first described in the late 1800's, long before the estimated date of the first human case of human immunodeficiency virus (HIV) infection. Although relatively rare in the United States, classic KS is, in fact, the most common subtype seen in elderly Caucasian men. Here we describe a 70-year-old man who presented with a 5-week history of a well demarcated, erythematous to violaceous papule on the sole that measured approximately 4 mm in diameter. When it was first noticed, the lesion appeared pink but darkened and showed slow growth by the time the patient presented for evaluation. The papule was neither painful nor itchy. Notably, the patient was on long-term HIV pre-exposure prophylaxis, was compliant with the medication, and underwent HIV testing every three months with a negative HIV screen shortly before the development of the lesion. Biopsy of the lesion showed a highly cellular vascular proliferation with atypical spindle cells forming interlacing fascicles. Plasma cells and lymphocytes were present and there were areas of erythrocyte extravasation. The atypical spindle cells showed positivity for CD31 with nuclear expression of HHV8. The lesion likely represents the classic form of KS given his negative HIV screen and lack of immunosuppression. This case serves as a valuable reminder that KS is not solely an AIDS defining illness, even in a patient at high risk for HIV.