We report a case of spinal seeding of a pilocytic astrocytoma of the chiasma opticum. Microscopic examination of the optic nerve tumor and the spinal tumor showed the same pathological patterns, without any signs of anaplastic transformation. The clinical course demonstrates the low growth rate of this kind of tumor, but spinal metastasis has not yet been described. We discuss different pathophysiological explanations of this atypical biological behavior with reference to the literature.