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Pediatric Myxopapillary Ependymomas: Clinico-pathological Evaluation


      PURPOSE: Myxopapillary ependymomas (MPE) have an indolent clinical course, corresponding to WHO Grade I designation. 13 pediatric MPEs have been reported in the literature to show “anaplastic features”, including elevated proliferative activity (≥5 mitoses per 10 high-power fields and/or Ki67 labeling index of >10%), necrosis, and microvascular proliferation. No consensus exists regarding the prognostic significance of such features. PROCEDURE: Retrospective clinicopathologic review of pediatric MPEs diagnosed between 1996-2018 at Mayo Clinic. RESULTS: The study included 8 pediatric MPEs (6 male; age range 7.52-16.88 years). 3 had disseminated disease at presentation. All patients underwent surgical resection (7 gross-total; 1 subtotal). 5 cases harbored ≥5 mitoses per 10 high-powered fields (range: 5-9), 3 of which showed necrosis (2 with disseminated disease). Following surgery, 2 patients received radiation; one with widely disseminated disease and another with increased mitotic activity and necrosis; neither has recurred at last follow-up (1.18 and 3.19 years). 2 patients with disseminated disease, elevated mitotic activity, and necrosis had new metastatic disease/progression of non-resected metastatic foci (2.6 and 26.8 months). Both received radiation therapy and have remained progression free (3.01 and 9.34 years). All patients are alive (median follow-up 1.31 years, range: 0.66-11.75 years). CONCLUSION: Our findings suggest that among pediatric MPEs, the concurrent presence of elevated mitotic activity and necrosis may be associated with a more aggressive clinical course, warranting closer surveillance and consideration of adjuvant therapies such as radiation. Attention to the presence of mitotic activity and necrosis may help identify children at higher risk for tumor recurrence/progression.