A Missed Differential in an Extra-Axial Lesion with Calvarial Involvement

Supratentorial extra-axial anaplastic ependymoma: a rare case report

Introduction and importance

Ependymomas are central nervous system tumors arising from the ependymal lining of the ventricle and spinal cord. Supratentorial extra-axial ependymomas are very rare, most commonly affecting the pediatric population and rarely in adults.

Case presentation

The authors report a case of a 71-year-old female with a headache and blurred vision. An MRI scan revealed a lesion at the parafalcine region of the occipital lobe. A parieto-occipital craniotomy was performed. When the dura was opened during the operation, the extra-axially located, well-circumscribed, dirty yellow-white tumor dissected from the surrounding tissue was excised entirely by microdissection. Histopathological examination revealed supratentorial extra-axial anaplastic ependymoma. The patient received postoperative radiation therapy (54 Gray over 30 fractions). No recurrence of the tumor was observed during the 4-year follow-up.

Discussion

Supratentorial ependymomas at the extra-axial region are uncommon; extra-axial anaplastic ependymoma and meningiomas have similar radiological findings, such as a dural tail, subarachnoid plane, and diffuse enhancement after contrast injection. This close similarity might cause misdiagnoses. Total surgical resection was followed by adjuvant radiotherapy and close follow-up in the gold standard of the treatment.

Conclusion

The authors report a rare case of anaplastic ependymomas located at the extra-axial region. Anaplastic tumors are prone to recurrence despite total resection and radiation therapy; hence, a close follow-up is warranted.

Supratentorial extra-axial RELA fusion-positive ependymoma misdiagnosed as meningioma by intraoperative histological and cytological examinations: a case report

Background

Dura-attached supratentorial extra-axial ependymoma is a very rare type of tumor, with only nine reported cases. Preoperative diagnosis of dura-attached supratentorial extra-axial ependymoma is difficult and often radiologically misdiagnosed as a meningioma. We report a case of dura-attached supratentorial extra-axial ependymoma that was misdiagnosed using intraoperative histological and cytological examinations.

Case presentation

A 26-year-old Japanese man with headache and nausea was referred to our medical facility. Magnetic resonance imaging revealed a cystic mass of 70 × 53 × 57 mm in the left temporoparietal lobe. A peritumoral band with hyperintensity on T2-weighted imaging was observed at the periphery of the lesion, suggesting an extra-axial lesion with no apparent connection to the ventricle. A dural tail sign was also noted on the gadolinium-enhanced T1-weighted image. Preoperative clinical diagnosis was meningioma. Proliferated tumor cells in sheets with intermingled branching vessels were observed in the frozen tissue. Perivascular rosettes were inconspicuous, and the tumor cells had rhabdoid cytoplasm. The tumor was intraoperatively diagnosed as a meningioma, suspected to be a rhabdoid meningioma. Perivascular rosettes were evident in the formalin-fixed paraffin-embedded tissues, suggesting ependymoma. The tumor cells had eosinophilic cytoplasm without a rhabdoid appearance. Anaplastic features, such as high tumor cellularity, increased mitotic activity, microvascular proliferation, and necrosis, were observed. Ependymal differentiation was confirmed on the basis of ultrastructural analysis. Molecular analysis detected C11orf95-RELA fusion gene. The final diagnosis was RELA fusion-positive ependymoma, World Health Organization grade III.

Conclusion

Owing to its unusual location, dura-attached supratentorial extra-axial ependymomas are frequently misdiagnosed as meningiomas. Neuropathologists should take great precaution in intraoperatively diagnosing this rare subtype of ependymoma to avoid misdiagnosis of the lesion as other common dura-attached tumors.