A Comprehensive Study on Squash Smear Cytology with Correlation to Histomorphological and Clinicoradiological Findings in Central Nervous System Lesions

Abstract

Objective: To highlight the cytomorphological variations observed in lesions of the CNS and the accuracy of diagnosis made in squash preparation as compared to histopathology as the standard method of diagnosis and correlate the histopathological diagnosis with the clinical & radiological diagnosis.

Methods: A total of 100 sequential cases that were suitable for both squash cytology (cytopathology) and paraffin section histopathology (histology) were examined. Biopsy smears were subjected to rapid hematoxylin and eosin staining along with May–Grünwald–Giemsa staining for cytological evaluation. Concordance was reported with 95% confidence intervals calculated using the Wilson score method. Chance-corrected agreement was assessed using the multi-class Cohen’s kappa coefficient and interpreted according to the Landis and Koch benchmarks. Sensitivity, specificity, predictive values, and accuracy were calculated for each lesion category on a one-versus-rest basis.

Results: From those cases examined, a category of diagnosis could be made by the squash cytology in each. Cytohistological concordance was 95.0%, with almost perfect agreement (kappa 0.94). Intra-group concordance was seen in glioma cases (30/33, 90.9%), meningioma cases (18/19, 94.7%) and craniopharyngioma cases (4/5, 80.0%) and was 100% for the remaining other lesions. With regards to the overall accuracy of the radiology compared to histopathology, the result was 94.0% (kappa 0.93). Five discrepancies were highlighted in the squash cytology, of which two could only be clarified by immunohistochemistry.

Conclusion: The amalgamation of clinical and radiological observations, along with histological confirmation, establishes squash smear cytology as a remarkable preoperative diagnostic technique for central nervous system disorders. It is also quick, accurate, and dependable. It is most reliable for common types and should be used with caution for rare tumours, for which the estimates in this series are not very precise.