Yet another utility for isocitrate dehydrogenase-1: Can it serve as an immunomarker to assess tumor margins in gliomas?
Shalinee Rao1, Aarthi Rajkumar2, Sandhya Sundaram3, Mintu Elizabeth Joyce4, Prathiba Duvuru3
1 Department of Pathology and Laboratory Medicine, All India Institute of Medical Science, Rishikesh, Uttarakhand, India
2 Department of Internal Medicine, Northeast Ohio Medical University, Canton Medical Education Foundation, Ohio, USA
3 Department of Pathology, Sri Ramachandra Medical College and Research Institute, Chennai, Tamil Nadu, India
4 Department of Pathology, Medical Trust Hospital, Kochi, Kerala, India
Department of Pathology and Laboratory Medicine, All India Institute of Medical Science, Virbhadra Road, Rishikesh - 249 201, Uttarakhand
Source of Support: None, Conflict of Interest: None
Background: Isocitrate dehydrogenase-1 (IDH1) mutation is now an established early event in gliomagenesis. The ability to detect this mutation by several techniques including immunohistochemistry makes it a significant marker for diagnosing and prognosticating gliomas. This study was done to assess the expression of mutant IDH1 in different grades of gliomas and evaluate its utility in differentiating reactive gliosis from glioma and defining surgical margins of these tumors in the operative specimens.
Materials and Methods: A total of fifty cases including equal number of Grade I, II, III, and IV gliomas and gliosis were included in the study. Formalin-fixed, paraffin-embedded tissue sections from these lesions were immunostained with IDH1 and Ki-67 antibody, and percentage of tumor cells that stained positive with these markers was assessed.
Results: Grades II, III, and IV showed consistent immunopositivity for IDH1. No immunostaining was noted in Grade I glioma and gliosis. Mean Ki-67 labeling index correlated with grades of gliomas with low activity in Grade I and high activity in Grade IV. Individual tumor cells infiltrating into adjacent normal brain parenchyma also stained positive with IDH1 antibody.
Conclusion: Immunostaining for IDH1 mutation can be utilized as a reliable marker in the precise diagnosis of diffuse gliomas and also in objective assessment of surgical margins to differentiate gliomas from gliosis.