Malignant intestinal schwannoma: a case report and a review of the literature in Japan.

We report the rare case of malignant intestinal schwannoma, not accompanied with von Recklinghausen's disease. The main tumor was located in the ileum with multiple small tumors observed on the peritoneum. Histologically the tumor was composed of spindle cells exhibiting a nuclear palisading formation and abnormal mitotic figures were observed. The tumor was immunohistochemically positive for S-100 protein, glial fibrillary acidic protein, vimentin and neuron-specific enolase, but negative for desmin. Electron microscopically the tumor cell exhibited morphological findings characteristic of schwann cell differentiation. On the basis of these results, the tumor was diagnosed as malignant schwannoma occurring in the ileum.