Solitary subependymal giant cell astrocytoma incidentally found at autopsy in an elderly woman without tuberous sclerosis complex.

Subependymal giant cell astrocytoma (SEGA) is a benign, slowly growing tumor typically occurring in the setting of tuberous sclerosis complex (TSC). However there are several reported cases in which patients with a solitary SEGA had no other stigmata of TSC. We describe a case of SEGA in a 75-year-old woman representing the oldest patient reported to-date. The patient had a history of radical vulvectomy for malignant melanoma (MM), and died of autopsy-confirmed widespread systemic metastasis. Postmortem examination of the brain revealed a single 2.1 x 1.0 x 0.8 cm intraventricular nodule in the lateral ventricle. Histologically, it was composed of interlacing bundles of spindle-shaped tumor cells with thin delicate processes admixed with relatively large pleomorphic cells with abundant glassy eosinophilic cytoplasm, as seen in a SEGA. Immunohistochemically, GFAP, S-100 protein, and neuron specific enolase were positive, and synaptophysin labeled a few tumor cells. Also noted were rare isolated MM cells within the tumor (i.e., tumor-to-tumor metastasis). Autopsy showed no manifestations of TSC systemically or intracranially. The histopathological differential diagnosis was limited and included giant cell ependymoma and, much less likely, giant cell glioblastoma and pleomorphic xanthoastrocytoma. This case illustrates that SEGA can be found incidentally in an elderly individual with no associated symptoms and also indicates that SEGA can occur outside the setting of TSC. Tumor metastasis to an occult SEGA is extremely rare.