Extracranial meningioma in the parapharyngeal space.

A case of extracranial meningioma in the parapharyngeal space is reported. A 24 year old woman presented with swelling and tenderness of the parapharyngeal region. A tumor was palpable in this region, and the tumor was surgically removed. Macroscopically the tumor occurred from the portion between the axis and atlas. Histologically the tumor cells, which had oval nuclei and a slightly eosinophilic cytoplasm, proliferated in fibrous connective tissues to form small nests. As the cell borders were not clear, the tumor structure appeared to be syncytium-like. Immunohistochemically the tumor cells were positive for anti-vimentin antibodies, anti-S-100 protein antibodies and anti-epithelial membrane antigen (EMA) antibodies in part. Electron microscopically the tumor cells had complex interdigitations of their adjacent plasma membranes. These were studded with many desmosomes. Bundles of intermediate filaments were visible in the cytoplasm. On the basis of the clinical, histological, immunohistochemical and electron microscopical features, the tumor was diagnosed as extracranial meningotheliomatous meningioma. The parapharyngeal space is an extremely rare location for extracranial meningioma, and our case is the first in Japan as far as we know.