Abstract
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.