# Case report on an extremely rare type of ependymoma arising from the thigh

## TL;DR

A rare case of ependymoma, typically a brain/spine tumor, was found in a patient's thigh and treated successfully with surgery and radiotherapy.

## Contribution

This paper reports an extremely rare case of extra-neural ependymoma arising from the thigh and emphasizes the need for CNS evaluation in such cases.

## Key findings

- The tumor was localized to the thigh with no central nervous system involvement.
- The patient remained recurrence-free for 3 years after extensive resection and radiotherapy.
- Extra-neural ependymomas should be treated as low-grade tumors due to higher recurrence/metastasis risk.

## Abstract

Ependymomas are neuroepithelial neoplasms of the central nervous system that arise from the precursor cells lining the ventricular system and the central canal of the spinal cord. Herein, we report a case of an extremely rare type of ependymoma arising from the thigh. Then, a literature review was performed.

An 87-year-old female Japanese patient presented with a chief complaint of a mass on the medial aspect of her right thigh. Pathology revealed a grade 2 extra-neural ependymoma. PET-CT and brain MRI showed no neoplastic lesions in the central nervous system, and the tumor was localized only in the right thigh. The tumor was growing and was treated as a low-grade tumor with extensive resection and postoperative adjuvant radiotherapy. The patient has been alive for 3 years, without postoperative recurrence or complications.

This case presents a rare extra-neural ependymoma of central nervous system origin arising in the thigh. The pathogenesis is unknown, but a search for neoplastic lesions in the cerebrospinal cord is warranted. Extra-neural ependymomas should be treated as low-grade tumors because they are more prone to recurrence and metastasis than ordinary ependymomas.

We experienced an extremely rare extra-neural ependymoma arising in the thigh. A search for tumors in the central nervous system region of the cerebrospinal cord, previous literature, and clinical, imaging, and pathological findings should be consulted to determine a treatment strategy.

•Ependymomas are neuroepithelial neoplasms of the central nervous system.•Experienced extra-neural ependymoma arising from the thigh that has very rarely reported.•Ependymomas located other than above or below the tent are considered Grade II.•The patient was treated with low grade malignant tumor(gradeIII) based on clinical findings of expansion tendency.

Ependymomas are neuroepithelial neoplasms of the central nervous system.

Experienced extra-neural ependymoma arising from the thigh that has very rarely reported.

Ependymomas located other than above or below the tent are considered Grade II.

The patient was treated with low grade malignant tumor(gradeIII) based on clinical findings of expansion tendency.