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The architecture of optic nerve gliomas with and without neurofibromatosis.

A retrospective clinicopathologic study of 34 patients with optic nerve glioma disclosed two important architectural tumor forms: circumferential-perineural pattern featuring tumor eruption and proliferation in the subarachnoid space correlating with the presence of neurofibromatosis, and an expansile-intraneural pattern correlating with the absence of neurofibromatosis. The 18 patients with neurofibromatosis had a mean age of 4.9 years at presentation and tended to be younger than the 16 patients without neurfibromatosis (mean age, 12 years). Instead of "arachnoidal hyperplasia," electron microscopic studies in the electron microscopic studies in the circumferential-perineural pattern showed tumor astrocytes admixed with reactive meningothelial cells, fibroblasts, and collagen in distended subarachnoid space. Florid invasion of the leptomeninges (arachnoidal gliomatosis) exhibited by many optic nerve gliomas in neurofibromatosis suggests that they are true neoplasms rather than hamartomas, but their frequent location in the distal anterior visual pathway often confers a good clinical prognosis.