The biological and clinical behaviour of pilocytic astrocytomas of the optic pathways.

The clinical and pathological findings in thirty patients with pilocytic astrocytomas of the anterior visual pathways were analysed. Our cases and those in the literature did not show positive correlation between the extent of surgical resection or irradiation or the presence of residual tumour, and the length of survival or degree of residual disability. Most of these tumours may be considered hamartoma-like growths, akin to developmental malformations, among which aggressive behaviour is exceptional. Their inherently benign nature, associated with long periods of dormancy and spontaneous regression, indicate that treatment should be conservative, and that a surprisingly favourable outcome can often be anticipated.