Pediatric Myxopapillary Ependymomas: A Clinicopathologic Evaluation

Area of Science:

• Pediatric neuro-oncology
• Neuropathology
• Clinical oncology

Background:

• Myxopapillary ependymomas (MPEs) are typically World Health Organization Grade I tumors with an indolent course.
• Anaplastic features, including high mitotic activity, necrosis, and microvascular proliferation, have been reported in a small subset of pediatric MPEs.
• The prognostic significance of these anaplastic features in pediatric MPEs remains unclear.

Purpose of the Study:

• To investigate the clinicopathologic features and outcomes of pediatric myxopapillary ependymomas.
• To evaluate the prognostic significance of anaplastic features, specifically elevated mitotic activity and necrosis, in pediatric MPEs.

Main Methods:

• Retrospective clinicopathologic review of pediatric MPEs diagnosed between 1996 and 2018 at Mayo Clinic.
• Analysis of patient demographics, tumor characteristics, treatment modalities, and clinical outcomes.
• Correlation of anaplastic features with disease progression and survival.

Main Results:

• Eight pediatric MPEs were identified, with 3 presenting with disseminated disease.
• Five cases showed elevated mitotic activity (≥5 mitoses/10 high-power fields), and 3 of these also exhibited necrosis.
• Patients with concurrent elevated mitotic activity and necrosis, particularly those with disseminated disease, showed aggressive behavior and progression, but remained progression-free after radiation therapy.

Conclusions:

• The concurrent presence of elevated mitotic activity and necrosis in pediatric MPEs may be associated with an aggressive clinical course.
• These findings suggest the need for closer surveillance in pediatric MPEs with these features.
• Consideration of adjuvant therapies may be warranted for pediatric MPEs exhibiting both elevated mitotic activity and necrosis.