Chordoid glioma with uncommon papillary and fusiform structures

Chordoid glioma (CG) is a rare, low-grade glioma predominantly located in the third ventricle, often presenting diagnostic challenges due to its similarity to other tumors. In this report, we presented the clinicopathological features of five cases of CG. The median age was 44 years, with a notable female predominance. All tumors were situated in the third ventricle and frequently misdiagnosed as craniopharyngioma via magnetic resonance imaging (MRI). Microscopically, all cases exhibited typical histopathological features of CG, which accounted for very small proportion in individual case. However, some also presented additional structures, including solid, fusiform, and papillary formations. Papillary and/or solid structures were notably present in cases of incomplete resection, whereas they were absent in cases of complete resection. Immunohistochemical analysis revealed that CK7 showed greater sensitivity in CG compared with pan-CK. Additionally, besides several common immunophenotypic features and PRKCA D463H mutation, diffuse and strong positivity for SOX2 was observed in all cases. Similarly, it was present in other gliomas, but not detected in craniopharyngiomas, chordomas and meningiomas. Therefore, these findings not only broadened the histological characteristics, immunological phenotypes, and prognostic factors associated with CG, while also reaffirmed its classification as a distinct tumor type.