Pseudopsammoma bodies in meningotheliomatous meningioma. A histochemical and ultrastructural study.

A case of meningioma arising from the right sphenoidal ridge is presented. Histologically, the tumour was composed of whorls of meningotheliomatous cells and many tumour cells containing intracellular inclusions were PAS positive, but diastase and neuraminidase resistant. The inclusions were named pseudopsammoma bodies by Kepes in 1961. The meningioma with pseudopsammoma bodies are a very rare entity and have been described in only 7 previous reports. We had an opportunity to examine one case of a meningioma with pseudopsammoma bodies. Electron microscopically, these substances were located in the intracellular spaces lined by microvilli. In earlier reports, the substances were said to be secretory products and a possibility of meningioma cell differentiation to secretory cell was postulated. Using the Concanavalin A staining method, the results of our present study strongly support this opinion.