Intraoperative squash cytology of central nervous system lesions: a single center study of 326 cases.

Cytology has been shown to be of great value in intraoperative consultations of central nervous system (CNS) pathology. Intraoperative smear cytology provides a rapid and reliable intraoperative diagnosis and guidance to the neurosurgeon during surgical resection and lesion targeting. It also helps the surgeon to monitor and modify the approach at surgery. The current study was undertaken to assess the accuracy and utility of intraoperative consultations for cytomorphological diagnosis by smear technique and correlate with histopathological diagnosis. A retrospective study of 326 cases of CNS intraoperative consultations was performed. Smears were prepared from the biopsy samples sent in isotonic saline for immediate processing and stained by the Haematoxylin and Eosin method. The cytomorphological features were noted and correlated with final histopathological diagnosis. Concordance between the intraoperative diagnosis and the final diagnosis was seen in 83.7% of cases. We demonstrated >95% accuracy for glioblastomas and >89% accuracy for meningiomas and schwannomas. A reduction of diagnostic accuracy was seen in oligodendrogliomas (60%) and anaplastic oligodendrogliomas (57.2%). Smear technique is a fairly accurate, relatively safe, rapid, simple, easily reproducible, and cost effective tool to diagnose brain tumors. Smear cytology is of great value in intraoperative consultation of CNS pathology.