Malignant epithelioid schwannoma of superficial soft tissue? A case report with immunohistology and electron microscopy

Abstract

Malignant epithelioid schwannoma [human] is a well-defined entity. However epithelioid tumours arising other than in a nerve trunk in a benign nerve sheath tumor or in neurofibromatosis are problematical. A case is described of a nodular tumor of the cheek which recurred twice without metastasis. Light microscopy showed an amelanotic epithelioid tumor. Immunohistology showed positive staining for vimentin and S100 protein and EM showed distinctive appearances suggestive of schwannoma. The differential diagnosis of the tumor is discussed compared with reported tumors resembling both melanoma and schwannoma and this may be a further example of the distinctive tumor reported as malignant epithelioid schwannoma of superficial soft tissues.