Germinoma of the optic nerve: case report.

This report concerns the unusual case of a germinoma primarily arising from the right optic nerve. The patient is a 31-year-old male who presented with progressive loss of vision, but with no clinical evidence suggestive of hypothalamic-pituitary dysfunction, including diabetes insipidus. The neuroimaging studies disclosed a tumor in the right optic nerve, but no intracranial tumors. Histologically, the tumor consisted of proliferating large clear cells with lymphocytic infiltration. The immunohistochemical studies revealed that the tumor cells expressed placental alkaline phosphatase. Perusal of the literature revealed that germinomas arising from the optic nerve have not been described heretofore. The histogenesis of the optic nerve germinoma is considered in relation to the proposed theory on the genesis of intracranial germ cell tumors.