Cellular schwannoma: a benign neoplasm sometimes overdiagnosed as sarcoma.

A case of cellular schwannoma originating in the left lumbar paraspinal region is described. The diagnosis was originally made on needle biopsy material. The histological examination is usually not sufficient to correctly diagnose this benign neoplasm. Bone erosion, neurological symptoms, caused by compression of the spinal roots, together with hypercellularity, pleomorphism and an occasional increase in mitotic activity, may lead to an erroneous diagnosis of malignancy. Immunohistochemistry and ultrastructural analysis are helpful in confirming the diagnosis. The recognition of this entity avoids unnecessary overtreatment of these patients.