Squash Cytology versus Frozen Section for Intraoperative Diagnosis of Lesions of Central Nervous System: A Cross-sectional Study

Introduction: Intraoperative assessment of neurosurgical specimens using squash cytology and frozen sections is helpful to plan extent of surgery and determine adequacy of representative tissue. Combination of these techniques has been shown to increase diagnostic accuracy and rate of concordance with final diagnosis. Aim: To assess usefulness of squash preparation and cryostat sections in making intraoperative diagnosis and to compare accuracy of squash cytology and frozen sections with respect to the final histopathological diagnosis. Materials and Methods: In this cross-sectional study conducted at a tertiary care hospital in Maharashtra, India, 110 neurosurgical specimens received for intraoperative consultation were assessed over the period of two years (January 2016- December 2017). The squash smears and frozen section diagnoses were compared with the final histopathological diagnosis and their diagnostic accuracy was determined. Sensitivity, specificity, positive predictive value and negative predictive value were calculated using appropriate statistical method. Results: Predominant age group in this study was 41-50 years (n=31, 28.1%) with male to female ratio of 2.23:1. Gliomas were most frequently encountered tumours (n=48) with Glioblastoma forming the commonest subgroup (n=19). The diagnostic accuracy, sensitivity and specificity of squash cytology were 90.72%, 93.50% and 80.01%, respectively. The diagnostic accuracy, sensitivity and specificity of frozen section were 95.87%, 97.40% and 90.01%, respectively. Conclusion: The diagnostic accuracy, sensitivity and specificity were better for frozen section than squash cytology. A more accurate intraoperative diagnosis was achieved by combining the methods.