POLYMORPHOUS HEMANGIOENDOTHELIOMA - A REPORT OF 2 CASES, ONE AFFECTING EXTRANODAL SOFT-TISSUES, AND REVIEW OF THE LITERATURE

Polymorphous hemangioendothelioma (PH) is a rare vascular neoplasm occ urring in lymph nodes. It has been considered a borderline malignant t umor, mainly because of a local recurrence in one of the three cases d escribed to date. This report adds two additional cases, one in which the tumor was extranodal. An extensive immunohistochemical study and t horough literature review were undertaken. The patients, a 55-year-old man and a 28-year-old man, both asymptomatic, presented with tumors i nvolving a left pulmonary hilar lymph node (3 cm) and the soft tissues of the left paravertebral region (4 cm), respectively. The tumors wer e composed of an admixture of solid, primitive vascular and ectatic an giomatous components, with both elements formed by uniform, polygonal cells. In one case, the cells marked for CD31 and factor VIII, and the other case was positive for CD34. Neither case marked for epithelial membrane antigen and keratin. One tumor partially replaced a lymph nod e, and no nodal tissue was identified in the other. Of the three previ ously reported cases of nodal PH, one had recurring and metastatic beh avior. PH is a rare, malignant vascular neoplasm that most frequently involves lymph nodes, but it can also affect extranodal locations.