MONDO_0016693 (subependymal giant cell astrocytoma) is a benign, slowly growing tumor (WHO grade I) typically arising in the wall of the lateral ventricles and composed of large ganglioid astrocytes. It is the most common CNS neoplasm in patients with tuberous sclerosis complex and typically occurs during the first two decades of life. (WHO). Also known as: SEGA, subependymal giant cell astrocytic neoplasm, subependymal giant cell astrocytic tumor, subependymal giant cell astrocytic tumour, subependymal giant cell astrocytoma (morphologic abnormality).