Meningeal myofibroblastoma.

Myofibroblastoma is a recently described benign mesenchymal tumor. Only one case has been reported previously in the CNS. We report a second case of myofibroblastoma arising in the meninges in a 70-year-old woman who presented with visual changes. The histologic appearance was characterized by alternating areas of spindled and rounded cells separated by collagen and amianthoid fibers. Immunostaining demonstrated strong vimentin and focal smooth-muscle actin positivity; staining for epithelial membrane antigen, cytokeratin, S-100, desmin, myosin, glial fibrillary acidic protein, and factor VIII-related antigen was negative. Ultrastructurally, the myofibroblasts had features of both smooth-muscle cells and fibroblasts. Differentiating the benign myofibroblastoma from more aggressive meningeal sarcomas and meningeal meningiomas is important. The tumor most likely arises from myofibroblasts that probably reside in the meninges.