Overview: Low-Grade Glioma IHC FISH Panel
Introduction: The Low-Grade Glioma IHC FISH Panel is a diagnostic tool designed to diagnose low-grade glioma using FFPE tissue. In India, low-grade gliomas (WHO grade 2, diffuse astrocytoma/oligodendroglioma) account for ~15-20 percent of primary brain tumors (~20,000-25,000 new CNS tumors/year), with molecular markers (IDH1/2 mutation, 1p/19q codeletion) defining prognosis and guiding therapy (better survival with IDH-mutant/1p19q-codeleted tumors). High morbidity from under-testing in rural/low-SES patients with seizures/headache, limited neuropathology/IHC/FISH labs, delayed accurate subtyping leading to inappropriate radiotherapy/chemotherapy or missed targeted options. Per neuro-oncology practices aligned with ICMR and Indian Society of Neuro-Oncology guidelines, the test employs microscopy, IHC, FISH, and PCR for 9 markers (IDH1 R132H, IDH2, 1p/19q codeletion, ATRX, p53, Ki-67, etc.) over 1-2 days with high accuracy, valuable for integrated WHO classification. This diagnostic falls under cancer screening and targets patients with suspected low-grade glioma on MRI, addressing accurate detection to guide observation, surgery, or temozolomide/PCV. With elevated morbidity due to underdiagnosis, the test supports public health efforts by enabling precise molecular subtyping and improving glioma outcomes. Its FFPE-based approach ensures reliable tissue-based analysis.
Other Names: Glioma IHC FISH Pnl.
FDA Status: FDA approved, CLIA certified for molecular pathology/histopathology/oncology, compliant with 2025 standards.
Historical Milestone: IDH/1p19q testing standard since 2016 WHO update; in India, expanding in neuro-oncology centers.
Purpose: The test assesses 9 parameters including IDH1 to guide low-grade glioma diagnosis, molecular subtyping, inform prognosis/therapy.
Test Parameters: 1â€"9. IHC/FISH Markers (IDH1, IDH2, 1p/19q, etc.).
Pretest Condition: No fasting required; patients should have brain lesion biopsy.
Specimen: Formalin-fixed paraffin-embedded block (0.5â€"2 cm³), transported within specified times to maintain sample integrity.Sample Stability: Indefinite when properly stored in formalin/paraffin; testing possible long-term.
Medical History: Patients should provide details on seizures, headache, MRI findings.
Consent: Written informed consent is required, detailing the test's purpose, potential risks of inaccurate subtyping including wrong therapy, benefits of molecular profiling, and no additional discomfort (uses existing block).
Procedural Considerations: The test involves slide preparation, IHC/FISH/PCR by trained personnel to ensure accurate scoring, avoid artifacts, and provide detailed report within 1-2 days using provided controls. Laboratories must maintain a controlled environment, adhere to quality assurance protocols.
Factors Affecting Result Accuracy: Poor fixation, inadequate tumor content, or interpretation differences can affect results. Correlation with clinical evaluation or additional testing is recommended to confirm findings.
Clinical Significance: IDH-mutant + 1p/19q codeleted indicates oligodendroglioma (favorable), necessitating specialist input.
Specialist Consultation: Neuro-oncologists/neurosurgeons should be consulted for management.
Additional Supporting Tests: MRI, NGS for confirmation.
Test Limitations: Dependent on block quality; comprehensive approach required.
References: Indian Journal of Pathology 2024, Neuro-oncology Studies India 2023.
