Malignant peripheral nerve sheath tumors with divergent differentiation.

Malignant peripheral nerve sheath tumors are uncommon sarcomas of Schwann cell or fibroblastic derivation which occasionally show histologic evidence of focal divergent differentiation to rhabdomyosarcoma, osteosarcoma, chondrosarcoma, angiosarcoma, epithelial elements, or a combination thereof. The finding of these heterotopic elements in nerve sheath sarcomas is believed to illustrate the differentiating capacity of neuroectodermal tissue. The authors present the clinicopathologic features of 17 such tumors, which represent 14.7% of the malignant peripheral nerve sheath tumors in the authors' institutional experience. Most of the lesions were associated with von Recklinghausen's disease. These tumors do not seem to differ from ordinary malignant peripheral nerve sheath tumors in presentation, operative, gross, and microscopic features, response to therapy, or prognosis.