Comparison of IDH and ATRX by immunohistochemistry with 1p/19q co-deletion by FISH in Oligodendrogliomas

Objective: To determine 1p/19q co-deletion by Fluorescence in situ hybridization (FISH) based on positive expression of IDH and ATRX by immunohistochemistry (IHC) in oligodendrogliomas. Study Design: Cross-sectional study. Place and Duration of Study: Department of Histopathology, Armed Forces Institute of Pathology, Rawalpindi Pakistan, from Oct 2021 to Jun 2022. Methodology: A total of 58 cases of oligodendrogliomas having positive expression of IDH and ATRX were subjected to FISH for 1p/19q co-deletion. FISH results were correlated with clinicopathological parameters and IHC by using computer software SPSS version 23. Results: In this study, age range is from 14 to 79 years, with mean of 40 years. 30(52%) cases are <40 years of age and 28(48%) cases are ≥40 years of age. There are 33(57%) males and 25(43%) females with a male to female ratio of 1.3:1. At the time of presentation, 25(43%) patients had headache, 19(33%) had focal neurological deficit, and 14(24%) had seizures. 1p/19q co-deletion by FISH was positive in 51(88%) specimens, whereas it was negative in 7(12%) specimens. 1p/19q co-deletion was not significantly associated with age, gender and clinical symptoms (p-value >0.05). Sensitivity & diagnostic accuracy of IHC with FISH as gold standard showed that combined sensitivity of IDH and ATRX was 100% with diagnostic accuracy of 87.93% for oligodendrogliomas. Conclusion: It’s concluded that oligodendrogliomas can be diagnosed with combined positive expression of IDH and ATRX with sensitivity of 100% and diagnostic accuracy of 87.93% where FISH for 1p/19q co-deletion is not available