SOX10 immunohistochemical stain in differential diagnosis of posterior fossa tumors, a single centered study.

Abstract

Objective: To evaluate the diagnostic utility of SOX10 immunohistochemical staining in distinguishing posterior fossa tumors, particularly ependymomas and non-ependymomas. Study Design: Cross-sectional study. Setting: Department of Histopathology, Shaukat Khanam Memorial Cancer Hospital and Research Center, Lahore. Period: March 2025 to August 2025. Methods: This cross sectional study included 65 posterior fossa tumors. 33 ependymomas and 32 non-ependymomas: pilocytic astrocytoma, medulloblastoma, meningioma, diffuse midline glioma,andhemangioblastoma. Immunohistochemistry was performed using SOX10, OLIG2, GFAP, synaptophysin, SSTR2 and inhibin. Ependymomas were molecularly subclassified into PF-EPN-A and PF-EPN-B. Statistical significance was assessed using chi-square and Fisher’s exact tests (p < 0.05). Results: PF-EPN-A was the most common ependymoma subtype (81.8%), with older median age than PF-EPN-B (5.0 vs. 2.5 years; p = 0.031). SOX10 was negative in all ependymomas (0/33) but highly expressed in pilocyticastrocytomas (85%) and the single diffuse midline glioma (100%), with significantly higher positivity in non-ependymomas (56.3%; p < 0.001). Synaptophysin was uniformly positive in medulloblastomas (100%). Conclusion: SOX10 is a sensitive and specific marker for distinguishing pilocytic astrocytoma from ependymoma. Its routine use in diagnostic panels enhances accuracy, reduces interpretive uncertainty and supports improved clinical decision-making in pediatric neuro-oncology.