Anaplastic Kaposi's sarcoma: an uncommon histologic phenotype with an aggressive clinical course.

Anaplastic Kaposi sarcoma (KS) is an uncommon histologic phenotype of Kaposi's and one that is typically associated with a locally aggressive clinical course. We report a case of a 53-year-old human immunodeficiency virus-positive male, on highly active antiretroviral therapy 1 month prior to admission, who presented with fever, cough, respiratory distress, multiple skin lesions and cervical and inguinal lymphadenopathy not responding to multiple antibiotics. Microscopic examination of punch biopsies from the forehead and chest revealed a spindled cell neoplasm with marked cytologic atypia and scattered mitoses, features consistent with a diagnosis of anaplastic KS and confirmed by immunohistochemistry with HHV-8. Biopsy of an involved lymph node also revealed involvement by KS. Despite aggressive clinical treatment, the patient rapidly deteriorated and expired 1 week after the diagnosis of anaplastic KS was rendered. Our case underscores the aggressive clinical course of this uncommon histologic variant of KS and its recalcitrant clinical behavior.