Epitheloid hemangioendothelioma of the scalp. A case report with immunohistochemical and ultrastructural study.

A case of an epitheloid hemangioendothelioma of the skin and subcutaneous tissue of the scalp is described. Clinically and histologically a (metastatic) carcinoma had been considered in differential diagnosis. Of great help in recognition of the endothelial nature of this tumor was the immunohistochemical reaction with Factor-VIII associated antigen and Ulex europaeus antigen. Not only tumor cells in solid areas, but also intracytoplasmic vacuoles revealed positive staining. Thereby it could be shown, that this paranuclear vacuoles are actually compatible with developing capillary lumina. Only few tumor cells showed positive reaction with alpha-1-antichymotrypsin, pointing to a possible small histiocytic component of this tumor. Endothelial features of tumor cells and developing capillary lumina also could be demonstrated by electronmicroscopy.