Cellular schwannoma: a distinct pseudosarcomatous entity

Abstract

Eighteen cases of cellular schwannoma, a recently delineated benign entity, are described. These tumors present most often in middle-aged adults of either sex and show a predilection for the paravertebral region of the mediastinum and retroperitoneum. More than half the tumors macroscopically acrose from a nerve but none was associated with von Recklinghausen''s disease. The light microscopic features are remarkably consistent but are not immediately recognizable as neural in type. Means of distinction from a malignant nerve sheath tumor and from a variety of other soft tissue tumors are discussed. Immunohistochemical positivity for S-100 protein has been demonstrated in 17 of the 18 cases. Prolonged follow-up has revealed local recurrence in only one case; none has metastasized.