Unique vascular tumor primary arising in the liver and exhibiting histopathological features consistent with so‐called polymorphous hemangioendothelioma

Reported herein is an unusual vascular tumor primary arising in the liver and exhibiting unique histopathological features. A 47‐year‐old woman underwent left hepatectomy because of a large hepatic mass. On histology the tumor had a composite pattern, consisting of angiomatous, retiform and solid areas, formed by oval to cuboidal to spindle cells, that expressed only endothelial markers (CD31 and factor VIII‐related antigen). These findings led to the diagnosis of a low‐grade vascular neoplasm with morphological features consistent with so‐called polymorphous hemangioendothelioma. The tumor was completely resected. At 24 month follow up the patient was alive, without evidence of disease. Polymorphous hemangioendothelioma is a rare vascular neoplasm, with borderline malignant potential, which usually occurs in lymph nodes and, rarely, at extranodal sites. Its classification as an entity has been questioned recently. The unusual morphological features of the present case, which do not fit neatly with any other recognized hemangioendothelioma subtype, indicate that the family of vascular tumors is broader than currently accepted. In addition the present case widens the spectrum of primary vascular tumors arising in the liver.