"Angioendotheliomatosis" is a diagnostic term used in histopathology to describe the proliferation of dilated vessels filled with mononuclear cells that have varying degrees of atypia. Either benign or malignant angioendotheliomatosis may exhibit this histologic pattern, and depending on the clinical course, cases are classified as either reactive angioendotheliomatosis or neoplastic angioendotheliomatosis. A case of neoplastic angioendotheliomatosis is presented and the literature reviewed with special attention to the pathogenesis of this condition.