Epithelioid hemangioendothelioma with actin+/cytokeratin+myoblast-like cells: Report of a case

Abstract

Michal Zamecnik

An unusual case of epithelioid hemangioendothelioma (EHE) with immunohistochemical positivity for cytokeratin (CK), alpha-smooth muscle actin, and calponin (CALP) is presented. The lesion occurred in a 43-year-old man in the right frontal region, with clinical suspicion for an epidermoid cyst. It was excised completely. Grossly, an 8 mm nodule was well circumscribed, soft, and it had gray cut surface. Histologically, typical features of EHE were seen, such angiocentric localization, epithelioid cytomorphology with mild atypia, myxohyaline stromal matrix, a few slit-like vascular channels, and isolated vacuolated cells. In addition, the stroma contained numerous spindle cells resembling myoblasts or myofibroblasts. They showed, besides scattered positivity for vascular markers, focal positivity for CALP and diffuse strong expression of alpha-smooth muscle actin and pancytokeratin AE1/AE3. This observation of numerous actin+/CK+cells is unusual. The lesion resembled other CK-positive vascular tumors and actin-positive myofibroblastic lesions, all of which has to be considered in differential diagnosis.