Primary central nervous system tumors are an extremely rare cause of sudden, unexpected death in children as most patients develop symptoms because of increased intracranial pressure and seek medical attention. Rarely, a forensic pathologist may encounter a primary intracranial neoplasm in a pediatric decedent that was not suspected before death. Herein, we present a case of a supratentorial neuroepithelial tumor found at autopsy in a 3-year-old African American boy without any reported significant medical history. The tumor had significant mass effect and caused cerebral edema, which ultimately resulted in transtentorial herniation and death. The gross, histopathological, immunohistochemical, and ultrastructural findings were most consistent with an anaplastic ependymoma.