Evaluating Diagnostic Concordance of Intraoperative Crush Smears and Frozen Sections With Final Histopathological Diagnosis of Central Nervous System Malignancies: A Clinical Audit in a Tertiary Care Center, Sri Lanka

PURPOSE Intra operative crush smears and frozen sections play vital role in providing a rapid histopathological provisional diagnosis in many malignancies including central nervous system tumors. Moreover, it guides the surgeon for making critical decisions regarding the extent of resection and immediate patient management. This study aims in identifying the level of concordance between intraoperative crush smear cytology and frozen sections with final histopathological diagnosis. Furthermore, this study is invaluable in identifying the discordant cases and possible etiologies for the discordances. National Hospital, Galle is the major tertiary care center which benefits many provinces of Sri Lanka. Therefore, this study helps in improving the opportunities for improving diagnostic accuracy and quality control. METHODS A retrospective review was performed of 77 cases which were received during January 1, 2025 to December 31, 2025 to the department of histopathology. Data was retrospectively yielded from the request forms and virtual archives. RESULTS Among all the evaluated 77 cases, 65 cases (84.4%) showed diagnostic concordance between the intraoperative cytology and final histology. Results of intraoperative cytology were inconclusive in 4 (5.2%) cases. Out of the 8 discordant cases (10.4%), the commonest error was seen among the high-grade glial tumors (n = 7) which were mistaken for low grade glial tumors (n = 3), metastatic deposit of carcinomas(n=3) or a lymphoma (n = 01). A case of fibromatosis was cytologically diagnosed as a schwannoma (n = 01). CONCLUSION Multiple etiologies can be postulated for the discordances between the intraoperative cytology and the ultimate histological diagnosis. Intraoperative, non-representative tissue sampling such as tissue taken from the surrounding necrotic, hemorrhagic areas, inadequate sampling from the tumor or intertumoral heterogeneity are possible causes for the pre analytical errors. Causes for the analytical errors include excessive crush artifacts while smear preparation, preparation of thick smears with dense cellularity and poor quality in frozen sections. Identified interpretations challenges includes the overlapping histomorphology among tumor entities (e.g. high-grade glioma vs metastasis; lymphoma vs glioma) and interobserver variability. Correlation of clinical, radiological and histological diagnoses is crucial in the ultimate patient management.