Intraoperative diagnosis of central nervous system lesions: Comparison of squash smear, touch imprint, and frozen section

Background: Intraoperative diagnosis of central nervous system (CNS) lesions is of utmost importance for neurosurgeons to modify the approach at the time of surgery and to decide on further plan of management. The intraoperative diagnosis is challenging for neuropathologists. Aims: The study was undertaken to determine the accuracy of cytological techniques (crush smears and touch imprints), frozen sections of space occupying lesions of the CNS and compare it with histopathological diagnosis. Materials and Methods: A total of 75 specimens received intraoperatively were subjected to cytology and frozen section study. Results: Neoplastic lesions formed the major group with 62 (82.7%) cases while 13 (17.3%) were nonneoplastic. The diagnostic accuracy of "squash smears" was found to be 89.2%. "Touch imprints" showed diagnostic accuracy of 78.4%. The low accuracy of touch imprints was attributed to poor cellular yield. The diagnostic accuracy of "frozen section" was 75.7%. However, the overall diagnostic accuracy was 96%. Conclusion: We believe that the cytololgical methods and frozen sections are complimentary to each other and both should be used to improve the intraoperative diagnostic accuracy in the CNS lesion.