Meningeal malignant fibrous histiocytoma arising from a thoracolumbar myelomeningocele. Case report.

The authors present a case of malignant fibrous histiocytoma (MFH) involving a thoracolumbar myelomeningocele. The patient died of metastases 11 months after diagnosis, in spite of extensive surgery, radiation therapy, and chemotherapy. Meningeal involvement by MFH is very rare; 11 additional cases are reviewed. Glial fibrillary acidic protein staining is critical for proper histological diagnosis, as this tumor can be easily confused with pleomorphic xanthoastrocytoma or glioblastoma involving the meninges. Malignant degeneration within a myelomeningocele is also very rare. Eight additional cases from the literature are reviewed. Our case is the only one with MFH. Chronic irritation to the unrepaired congenital defect appears to be a key to the development of the malignancy. Prophylactic repair in infancy might prevent the occurrence of malignant degeneration.