Diagnostic Accuracy of Intraoperative Squash Smear Cytology in Central Nervous System Lesions With Histopathological Correlation and Idh-1 Immunohistochemical Expression in Astrocytic Tumours: a Cross-sectional Study
Year: 2026
Type: article
Study design: Observational Study
Abstract: Background: Intraoperative squash smear cytology provides rapid provisional diagnosis during neurosurgical procedures for central nervous system (CNS) lesions. Contemporary WHO classification of CNS tumours emphasizes integrated histomolecular diagnosis, with isocitrate dehydrogenase-1 (IDH-1) status critical for astrocytic tumours. This is study evaluated the diagnostic accuracy of squash smear cytology against histopathology and assessed IDH-1 expression in astrocytic tumours. Materials and Methods: This cross-sectional study was conducted in the Department of Pathology, Gajra Raja Medical College and J.A. Group of Hospitals, Gwalior, over one and half years. This cross-sectional study included 100 consecutive eligible patients undergoing neurosurgery for clinically and radiologically suspected CNS lesions with adequate squash cytology and histopathology samples were included. Squash smears were prepared intraoperatively, fixed, and stained with haematoxylin and eosin (H&E). Remaining tissue underwent routine histopathological processing (H&E-stained paraffin sections as gold standard). IDH-1 immunohistochemistry was performed on astrocytic tumours. Diagnostic concordance and accuracy were calculated. Data were analyzed using SPSS version 25.0. Results: Of 100 cases, the majority were aged 41–60 years (46; 46.0%) with male predominance (62; 62.0%). Astrocytoma Grade 3 was the most common histopathological diagnosis (18; 18.0%). Overall diagnostic accuracy of squash smear cytology was 88.0% (88 concordant, 12 discordant). Tumour-wise accuracy was 100% for nerve sheath tumours (9/9), medulloblastoma (7/7), oligodendroglioma (4/4), ependymoma (2/2), and lymphoma (1/1); 91.7% for meningioma (11/12) and metastasis (11/12); 83.9% for high-grade astrocytoma (26/31); 75.0% for low-grade astrocytoma (9/12); 87.5% for abscess (7/8); and 50.0% for vascular tumours (1/2). IDH-1 immunohistochemistry showed mutant expression in 25 cases (25.0% of total cohort), wild-type in 13 (13.0%), and not applicable in 62 (62.0%; non-astrocytic lesions). Conclusion: Squash smear cytology is a reliable, rapid, and cost-effective intraoperative diagnostic modality with good overall concordance to histopathology. Accuracy is highest in lesions with distinctive cytomorphology and lower in infiltrative or haemorrhagic lesions. Integration with histopathology and IDH-1 immunohistochemistry supports modern diagnostic approaches, particularly valuable in resource-limited settings.
Language: English
Subfield: Genetics
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W7204479870
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