Ultrastructural and immunohistochemical study of an adult case of chordoid meningioma.

A 64-year-old male patient presented with generalized convulsions. Magnetic resonance imaging revealed a large meningeal tumor with some cysts in the right frontal region. Surgical resections were performed three times, and local radiation therapy was administered twice over a period of 8 years for the treatment of tumor recurrences. The tumor tended to recur in spite of the surgical and radiation therapies. The tumor was diagnosed as a chordoid meningioma, and the second surgical specimen showed increasing nuclear atypia and mitoses in tumor cells. An immunohistochemical study revealed the tumor cells were positive for vimentin, S-100 protein, and cytokeratin AE1/AE3. An electron microscopic study revealed intracytoplasmic vacuolar spaces, loosely connected interdigitating cell processes with intermediate junctions, and extracellular spaces which contained fluffy granular intercellular substances. The tumor cell surfaces displayed pseudopodia which extended into the intercellular spaces and the tumor cells had moderate quantities of cytoplasm containing abundant mitochondria and glycogen granules. According to the ultrastructural features in the past reports of chordoid meningiomas, these meningiomas are suspected to have a mixture of the characteristic ultrastructural features of meningothelial meningiomas and chordoid sarcomas.