Stratification of diffuse gliomas based on IDH mutation status - First and the largest tertiary care hospital study of Rajasthan

Dr. Tyagi Surabhi; Dr. Kalla Amrit Raj; Dr. Sharma B.S

Volume : IX, Issue : VIII, August - 2020

Stratification of diffuse gliomas based on IDH mutation status - First and the largest tertiary care hospital study of Rajasthan

Dr. Tyagi Surabhi, Dr. Kalla Amrit Raj, Dr. Sharma B. S

Abstract :

Background – All astrocytic tumors were first grouped together but are now classified on the basis of IDH1/IDH2 mutation irrespective of astrocytic or oligodendroglial lineage as �diffuse gliomas�. The most notable change is the IDH status and 1p19q co–deletion for oligodendroglioma. Most of the genetic parameters can be assessed by immunohistochemistry or FISH. Gliomas with mutations of IDH genes are classified as IDH–mutant and those having unmutated IDH genes are classified as IDH wild–type. Objective – To study usefulness of IDH1 mutation status in diffuse gliomas by Immunohistochemical study. This is the first and the largest study done in a tertiary care centre in Rajasthan to the best of our knowledge. Material & methods –This is a tertiary hospital based study of sixty cases of diffuse gliomas. IHC was done using primary antibody against the these antigens‑ IDH1 R132H (1:50 dilution, Nova), ATRX (1:100 dilution, Sigma), p53 (dilution 1:1000, Santa Cruz biotechnology), MIB1 (RTU, Dako) Results & Conclusion – IDH1 mutations were found in 60% cases with frequency being higher in oligodendroglial tumors as compared to astrocytic tumors. Diffuse and anaplastic astrocytomas had nearly equal frequency of 78.57% & 80% respectively while frequency of IDH1 mutation in grade II oligodendroglioma was 100% and in grade III was 81.81%. However, in our study, 6 cases which had astrocytic tumor morphology on H&E showed heterogeneous positivity for ATRX and were advised IDH2 sequencing and 1p 19q codeletion. Maximum positivity of p53 was observed in glioblastomas. Our study did not show p53 positivity in most of the diffuse astrocytomas. No correlation of IDH1 and p53 mutation was found.