Intraocular Myxo-Papillary Ependymoma versus Retinal Gliosis Mimicking Uveal Melanoma: Report of 2 Adult Patients with Clinical, Imaging, and Histopathologic Features.

Introduction: To report two cases of primary retinal ependymoma occurring in adults, both enucleated following initial suspicion of uveal melanoma. Uveal melanoma is the most frequent primary tumor of the eye in adults but other rare benign intraocular tumors such as leiomyoma, adenoma or ependymomas may also occur. To diagnose them properly is critical to adapt the patient's management, prognosis and follow-up. Ependymomas are exquisitely rare glial tumors arising from the retina, with only three cases reported yet. Primary clinical diagnosis and distinction between benign or malignant tumor is usually not possible without enucleation and histopathologic analysis. Ependymomas are glial tumors, usually occurring during childhood and arising within the central nervous system (CNS, brain or spinal cord). However, they may also occur outside the CNS, either as a primary or a secondary location. Case Presentations: Case series from two adults aged 41 and 42 years with blindness and painful eye due to neovascular glaucoma who were enucleated for intraocular tumors. Imaging demonstrated in both cases nonspecific vascularized solid tumors consistent with uveal melanoma. Histopathologic findings showed radial arrangement of cuboidal to elongated tumor cells around hyalinized fibrovascular cores, presence of myxoid material and diffuse expression of GFAP but not Olig2, orienting the diagnosis to myxopapillary retinal ependymomas. No primary of distant CNS location was identified and follow-up at one and 3 years was favorable. Conclusions: Intraocular ependymoma is a rare intraocular primary retinal tumor which can mimic uveal melanoma at ocular fundus examination and imaging. The diagnosis requires histopathology after enucleation, and can mimic reactive retinal gliosis, whether ependymomas can arise from retina or if retinal gliosis can have ependymoma characteristics is still to be determined. Survival and metastatic prognosis after surgery are favorable according to our experience and previously published cases, confirming the presumed benign nature of the lesions.