Biphasic high-grade cerebellar glioma with epithelial-like components: challenges in integrated diagnosis imposed by limited sampling
摘要
A 67-year-old man presented with bilateral diplopia and gait instability. Brain magnetic resonance imaging revealed two adjacent lesions in the right middle cerebellar peduncle: a 2.7-cm cystic lesion with an enhancing mural nodule and a 1.7-cm ring-enhancing nodule with surrounding edema and associated brainstem compression. Biopsy followed by surgical resection demonstrated a biphasic tumor composed of glioma-like and epithelial-like components. Immunohistochemically, the glioma-like component expressed GFAP and OLIG2, whereas the epithelial-like component lacked glial and epithelial lineage markers and exhibited a high proliferative index (Ki-67 labeling index, 50%). Aberrant calponin-1 expression was observed in both components but was not associated with definitive smooth muscle or myoepithelial differentiation. DNA methylation profiling did not yield a definitive classification and demonstrated borderline similarity to established high-grade glioma classes, clustering near the glioblastoma, IDH-wild-type, midline subtype. Molecular analysis of the epithelial-like component was not feasible due to limited tissue availability, preventing assessment of clonal relatedness between components. This case illustrates the diagnostic challenges posed by intratumoral heterogeneity and sampling limitations in adult cerebellar high-grade gliomas. This report highlights the interpretive constraints of current histopathological and molecular classification frameworks when confronted with spatially heterogeneous tumors and incomplete sampling, rather than defining a novel tumor entity.