Utility of Intraoperative Imprint Cytology in Diagnosis and Grading of Glioma: A Cross-sectional Study

Abstract

Introduction: Gliomas are most common primary Central Nervous System (CNS) neoplasm in adult population. Gliomas predominantly arise from brain parenchyma. Invasion of adjacent normal parenchyma is a prominent feature. Aim: To study the epidemiological incidence of glial tumours and the viability and accuracy of intraoperative cytology in diagnosis and grading glial tumours. Materials and Methods: A cross-sectional study was done on 30 patients who underwent excision surgery at Department of Neurosurgery at Institute of Postgraduate Medical Education and Research IPGMER and SSKM, Kolkata, West Bengal, India. Clinically, radiologically confirmed cases of Space Occupying Lesion (SOL) of brain with a history of neurosurgical intervention were included. Patients medically unfit for surgery or without radiological evidence of SOL in the brain were excluded from the study. Intraoperative imprint touch cytology of the specimens was done. Part of the tissue was kept for Formalin Fixation and Paraffin Embedding (FFPE) and subsequent histopathological examination were done. Results of intraoperative imprint cytology were compared with final histopathology report and grading. Matthews correlation coefficient t-test, Kohen's Kappa (κ), Chi square test (χ2 ) were used for the statistical analysis. A p-value of p<0.5 was considered statistically significant. Results: About 10 (33.3%) of the patients presented with frontal lobe lesion. Out of 30 cases 29 (96.6%) were histologically confirmed to be of glial origin, 1 (3.3%) was metastasis from other tumour. These 29 cases were diagnosed as different glial neoplasm on intraoperative imprint cytology and were confirmed by histology. According to histological subtype 12 (41.37%) were glioblastoma, 10 (34.48%) were diffuse astrocytoma, 3 (10.34%) were pilocytic astrocytoma, 3 (10.34%) was ependymoma. Intraoperative impression cytology diagnosis was compared with confirmatory histological diagnosis. Sensitivity and specificity was found to be 93% and 50%, respectively, Positive Predictive Values (PPV) 96%, Negative Predictive Values (NPV) 33%, diagnostic accuracy 89.65% and p<0.5 was statistically significant. Conclusion: In the present study, confirmatory histopathology report showed a significant association with imprint cytology report. Hence, it can be concluded that intraoperative imprint cytology is a fairly accurate, rapid and inexpensive method of diagnosis and grading of gliomas.