A human ganglioglioma containing paired helical filaments.

Neurofibrillary tangles composed of paired helical filaments were found in a human ganglioglioma. This is the first reported occurrence of neurofibrillary tangles in a neoplasm. These tangles were visible light microscopically with hematoxylin-eosin and Bodian's stains. They were confirmed as neurofibrillary tangles with Congo red staining under polarized light and with thioflavine S fluorescence. Untrastructurally, the tangles were composed of 10-nm filaments twisted in a helix with 80 nm between constructions. Thus, neoplastic proliferation does not preclude production of paired helical filaments. Cells grew from explants of this tumor, but no paired helical filaments were found in the cells examined. Two other gangliogliomas and normal brain tissue studies by the same procedures did not show paired helical filaments. Gangliogliomas that contain neurofibrillary tangles provide an alternative source of abnormal filaments for analysis.