Granular cell tumour in the third ventricle. Case report with histological, electron-microscopic, immunohistochemical and necropsy findings.

A rare granular cell tumour was found in the third ventricle of a 56-year-old woman. Histological and electron-microscopic features obtained from the biopsy material were identical to those of previously recorded cases. Immunohistochemical study demonstrated vimentin but not S-100 protein in the tumour cells. The possibility should be re-considered that granular cell tumours may have more than one cell of origin.