Ependymoma with "granular cell" features: report of two cases

Ependymoma with C11orf95-MAML2 fusion: presenting with granular cell and ganglion cell features

C11orf95-RELA fusion or, less frequently, YAP1 fusion is recurrently detected in most cases of supratentorial ependymoma. Other fusions have rarely been reported in some cases of supratentorial ependymoma, and little is known about their pathological or clinical features. Here, we present a case of supratentorial ependymoma with unusual pathological findings and C11orf95-MAML2 fusion. A 23-year-old man was admitted to our hospital because of headache and vomiting. Magnetic resonance imaging revealed a cystic lesion in the right frontal lobe, and gross total resection of the tumor was performed. Pathologically, the tumor was mainly composed of typical ependymal lesions with perivascular pseudorosettes and contained some atypical lesions, with granular and ganglion cell features. The tumor was diagnosed as anaplastic ependymoma, which was classified as grade III on the World Health Organization scale, and found to be RELA fusion-positive in the DNA methylation analysis. However, the tumor was negative for C11orf95-RELA fusion, and RNA sequencing detected C11orf95-MAML2 fusion. The patient has not received adjuvant therapy and has remained alive without any evidence of disease for 30 months, suggesting that the prognosis might be better than that of typical C11orf95-RELA fusion-positive ependymoma.