Diagnostic accuracy of squash cytology and role of GFAP immunoexpression in glial tumors

Introduction: Intraoperative squash technique provides rapid and reliable diagnosis which is helpful to monitor or modify the treatment approach. We carried out the present study to compare the accuracy of squash preparation with histopathological diagnosis and also to study the role of GFAP immunostaining in gliomas. Material and Methods: Clinicoradiologically diagnosed 127 cases of gliomas were subjected to both squash smear cytology and histopathological examination; also to GFAP staining using monoclonal antibody (EP672Y clone). Taking histopathology as gold standard, diagnostic accuracy and statistical values were calculated. Immunohistochemical analysis was compared with final diagnosis. Results: Overall diagnostic accuracy of squash cytology was observed as 95.2% (sensitivity=99.1%, PPV= 99.1%). All low grade astrocytomas and ependymoma showed strong diffuse positivity while high grade astrocytomas were focally reactive. Negative immunoexpression was seen in case of oligodendroglioma and pituitary adenoma. Conclusion: Squash cytology is of great value in rapid intraoperative consultation of gliomas. GFAP can be used as an adjunctive tool to verify the astroglial differentiation especially in diagnostically difficult cases.