Correlation of intraoperative squash smear and histopathology in central nervous system lesions: A 6-year retrospective study in a tertiary care hospital in Kerala

Abstract

Intraoperative squash smear cytology is considered to be of great value in intraoperative consultation of CNS pathology. It is a simple and reliable tool for rapid intraoperative diagnosis of CNS tumors. The study was undertaken to assess the accuracy of intraoperative squash smear in the diagnosis of CNS lesions and to correlate the squash cytology diagnosis with histopathological diagnosis taking the latter as the gold standard. A retrospective study of 38 cases of CNS lesions from which samples were collected by surgery or biopsy for intraoperative consultations and histopathological diagnosis. Radiologically confirmed cases were only included in the study. Smears were prepared from the biopsy sample obtained at the time of operation and were stained with hematoxylin and eosin. Remaining tissue submitted for histopathology was later correlated with intraoperative cytology diagnosis. Out of 38 cases, histopathological diagnosis was compatible with cytological diagnosis in 36 cases, two cases showed discrepancies. The diagnostic accuracy of squash cytology was 94.73%. Even though two cases were diagnosed differently in cytology, it was proved to be a malignant tumor both in squash cytology and histopathological diagnosis. Hence sensitivity, specificity, positive predictive value and negative predictive value in detecting the neoplastic condition on cytology was 100% respectively. Squash smear is a rapid, self-sufficient and cost effective method for the intraoperative diagnosis of CNS tumors. It can be considered as a mirror image to histopathological diagnosis and is of great value in intraoperative consultation of CNS pathology.