Mixed Tumor with Subependymoma and Ependymoma Features: A Case Report and Review of the Literature

Background: Subependymomas are slow-growing, benign ependymal neoplasms histologically characterized as grade I tumors. On the other hand, ependymomas are higher-grade tumors of neuroectodermal origin that share a predilection for the fourth ventricle. Given that these tumors can occur simultaneously as mixed lesions, features that raise clinical suspicion of a combined pathology warrant surgical resection for definitive diagnosis and potential cure. Case report: A 61-year-old ambidextrous male presented with headache and an MRI demonstrating a lesion involving the fourth ventricle. Imaging demonstrated faint contrast enhancement and growth through the foramen of Luschka, rendering the possibility of an ependymoma or a mixed entity. The patient underwent gross total resection, with pathology confirming a mixed subependymoma-ependymoma. He was discharged neurologically intact and underwent external beam radiotherapy. Conclusions: Mixed subependymoma-ependymomas are exceedingly rare tumors often misdiagnosed as pure subependymomas. In the setting of a mixed pathology, however, the lesion warrants neurosurgical intervention and requires the more aggressive management that is standard for ependymomas. While the exact origin of these mixed neoplasms remains unknown, further investigation using molecular methods will likely help elucidate the pathogenesis and mechanisms that underlie combined subependymoma-ependymoma tumors.