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Diffuse astrocytoma with mosaic IDH1-R132H-mutant immuno-phenotype and low subclonal allele frequency
Katherine M Morgan1, Shabbar Danish2, Zhenggang Xiong1,3
1Department of Pathology and Laboratory Medicine, Robert Wood Johnson Medical School, Rutgers University, New Brunswick, New Jersey, USA.
Intractable & Rare Diseases Research
|March 9, 2022
Summary
This case study describes a diffuse astrocytoma with a mosaic isocitrate dehydrogenase (IDH)1-R132H mutation. The findings highlight intra-tumoral molecular heterogeneity in gliomas, impacting classification and management.
Area of Science:
- Neuro-oncology
- Molecular Pathology
- Genetics
Background:
- Molecular alterations are key in glioma classification per the World Health Organization (WHO) integrated genotype-phenotype approach.
- Diffuse astrocytomas are a type of glioma characterized by specific molecular and histological features.
Purpose of the Study:
- To present a rare case of diffuse astrocytoma exhibiting a mosaic isocitrate dehydrogenase (IDH)1-R132H-mutant immunophenotype.
- To discuss the implications of intra-tumoral molecular heterogeneity in glioma classification and patient management.
Main Methods:
- Histopathological examination including immunohistochemistry for GFAP, Olig2, ATRX, and IDH1-R132H.
- Cytogenetic analysis for 1p/19q co-deletion.
- Next-generation sequencing (NGS) to determine mutation allele frequency.
Main Results:
- A diffuse astrocytoma case (WHO grade II) presented with scattered IDH1-R132H positive cells, indicating a mosaic immunophenotype.
- Next-generation sequencing revealed a low subclonal allele frequency for the IDH1-R132H mutation.
- Absence of 1p/19q co-deletion was confirmed.
Conclusions:
- Gliomas can display heterogeneous molecular profiles, challenging traditional classification.
- Mosaic IDH1-R132H mutations and low allele frequencies necessitate advanced molecular characterization for accurate diagnosis.
- Understanding intra-tumoral heterogeneity is crucial for refining glioma classification and guiding clinical decisions.
