Clinicopathological and ultrastructural study in two cases of chordoid glioma

Chordoid glioma is a rare benign neoplasm of uncertain histogenesis occurring in the third ventricle/ /suprasellar region. Recently, data have emerged suggesting that chordoid glioma is a variant of ependymoma related to a specialised ependyma of the subcommisural organ or the lamina terminalis area. In this study, we report clinicopathological and ultrastructural findings in two chordoid glioma cases. In case 1, a tumour (1.5 cm in diameter) in a 62-year-old man invaded the anterior-basal part of the third ventricle in the lamina terminalis region. In case 2, a large tumour in a 51-year-old woman occupied the whole third ventricle. The tumour attached to the medio-basal hypothalamic region. Histologically, both cases revealed a distinct chordoma-like pattern and glial immunophenotype of tumour cells. Under the electron microscope the tumour cells exhibited microvilli, intercellular lumina, intermediate type junctions and focal basal lamina formations. These findings were similar to those previously reported in the chordoid glioma cases. Moreover, the intracytoplasmic cilia and subplasmalemmal pinocytic vesicles or caveoles were observed. The study supports the view of ependymal derivation of chordoid glioma. Its relation to lamina terminalis or infundibular/median eminence area presumably reflecting tumour origin from the modified ependyma of circumventricular organs of the third ventricle is discussed.