A rare case of a solitary peripheral nerve sheath sarcoma of the scalp

Summary Malignant peripheral nerve sheath tumors are rare and most often appear in the clinical setting of von Recklinghausen's neruofibromatosis. On rare occasions they are seen in patients lacking any of the overt stigmata of this systemic disease. We report on a case of a peripheral nerve sheath sarcoma (PNSS) on the scalp and the back of the neck of a 13-year-old female arising in a solitary benign neurofibroma with no evidence of systemic neurofibromatosis. The tumor was examined by ultrastructural and immunohistochemical techniques as well as by routine histopathology. It was defined as a peripheral nerve sheath sarcoma, fibrosarcomatous type, of poorly differentiated perineurial cell origin. The possible significance of histogenetic subclassification in terms of surgical management and the oncological approach as well as the prognosis is discussed.