Malignant optic nerve glioma. Report of a case with electron microscope study.

Optic nerve gliomas are rare, being responsible for I per cent. of intracranial tumours (Russell and Rubinstein, I 97 I) and 3 per cent. of unilateral rbital lesions (Reese, I963). 75 per cent. of patients are under the age of io years (Chutorian, Schwartz, Evans, and Carter, I964) and the association with neurofibromatosis is well established (Davis, I940; van der Hoeve, I925; Tym, I96 i). The benign glioma has been described as a 'congenital non-neoplastic hamartoma-like lesion with a distinctive self-limiting pattern of growth and morbidity' (Hoyt and Baghdassarian, I969). In contrast to this benign group, a malignant glioma with acute onset simulating optic neuritis and a rapidly progressive course has also been reported (Martin and Cushing, I923; Saeb0, 1949; Mattson and Peterson, I966; Condon and Rose, 1967). The present case, which exemplifies this malignant group, is reported with electron microscope findings.