A Comparison between the Diagnostic Accuracy of Frozen Section and Permanent Section Analyses in Central Nervous System

Objective: Using diagnostic pathological methods during surgery is a valuable means of determining the appropriate management for patients. Application of Frozen Section in CNS surgeries might face challenges due to friability of brain tissue and its relative inaccessibility. Various studies have evaluated the diagnostic acuity of frozen section compared to gold standard but results have been quite inconsistent. We conducted the present study to evaluate the accuracy of cryostat in diagnosing central nervous system tumors compared to the Gold Standard method. Methods: In this descriptive retrospective study, patients with definite diagnosis of central nervous system tumors made through histopathological evaluations were identified by reviewing the archives of pathology reports during 1996-2013. Demographic data, clinical history, radiologic findings and results of pathologic evaluations were extracted from the medical records and entered into SPSS statistical software v.22 for analysis. Results: A total of 405 patients diagnosed with CNS tumors were identified, of which 16 patients were not eligible and eventually 389 patients were included in the study. Regarding tumor category, subtype and grade, the results of the two methods were totally compatible in 303 patients (77.9%) and discrepant in 22.1% of cases. The tumors located in the middle fossa (p=0.031; OR=2.27; 95% CI: 1.08-4.79) and the posterior fossa (p=0.021; OR=2.46; 95% CI: 1.15-5.26) and the tumors biopsied using the stereotactic method (p=0.050; OR=2.42; 95% CI: 1.001-5.83) were associated with an increased chance of discrepant results between the two methods. Conclusion: Frozen section can correctly diagnose and affect the management of CNS lesions in 77.9% of cases. Finding ways to increase the sensitivity and specificity of this method and providing surgeons with more definite and exact intra-operative diagnosis can improve management of central nervous system lesions to a considerable degree.