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**Overview**: FISH Eosinophilic Leukemia Panel**Introduction**: The FISH Eosinophilic Leukemia Panel is a diagnostic tool designed to screen for eosinophilic leukemia using whole blood or bone marrow samples. In India, eosinophilic disorders (chronic eosinophilic leukemia, hypereosinophilic syndrome) are rare but associated with PDGFRA/PDGFRB/FGFR1 rearrangements and CBFB-MYH11 in some AML subtypes, guiding targeted therapy (imatinib for PDGFRA). High morbidity from underdiagnosis in rural/low-SES patients with persistent eosinophilia, organ damage (heart, lung), limited FISH access, delayed TKI leading to end-organ failure. Per cytogenetics practices aligned with ICMR and Indian Society of Hematology guidelines, the test employs FISH for PDGFRA/PDGFRB/FGFR1/CBFB rearrangements over 1-2 days with high sensitivity/specificity, valuable for molecular subtyping and therapy selection. This diagnostic falls under genetic cancer screening and targets patients with unexplained eosinophilia or suspected myeloid neoplasm, addressing accurate detection to guide imatinib or intensive chemotherapy. With elevated morbidity due to under-testing, the test supports public health efforts by enabling precise molecular diagnosis and improving outcomes. Its blood/bone marrow-based approach ensures reliable rearrangement detection.**Other Names**: FISH Eos Pnl.**FDA Status**: FDA approved, CLIA certified for cytogenetics/oncology, compliant with 2025 standards.**Historical Milestone**: Rearrangement FISH standard; in India, used in eosinophilia workup.**Purpose**: The test detects 2 parameters including PDGFRA/PDGFRB/FGFR1/CBFB rearrangements to guide eosinophilic leukemia assessment, identify actionable variants, inform therapy.**Test Parameters**: 1. PDGFRA/PDGFRB/FGFR1/CBFB Rearrangements, 2. Chromosomal Abnormalities.**Pretest Condition**: No fasting required; patients should have persistent eosinophilia or suspected leukemia.**Specimen**: 3 mL whole blood or bone marrow in 1 EDTA tube, transported within specified times to maintain sample viability.**Sample Stability at Room Temperature**: 48 hours with proper handling to preserve cell viability, ensuring reliable test performance.**Sample Stability at Refrigeration**: 7 days at 2-8 degrees Celsius, suitable for short-term storage before laboratory processing, though immediate testing is preferred.**Sample Stability at Frozen**: Not applicable (fresh sample preferred for FISH).**Medical History**: Patients should provide details on eosinophil count, organ symptoms, prior therapy.**Consent**: Written informed consent is required, detailing the test's purpose, potential risks of undetected rearrangements including organ damage, benefits of detection, and minimal discomfort from blood/bone marrow draw.**Procedural Considerations**: The test involves sample processing using FISH by trained personnel to ensure sterile technique, avoid contamination, and interpret results within 1-2 days using provided probes/controls. Laboratories must maintain a controlled environment, adhere to quality assurance protocols.**Factors Affecting Result Accuracy**: Delays beyond stability periods, improper storage conditions, or low eosinophil count can affect results. Correlation with clinical evaluation or additional testing is recommended to confirm findings.**Clinical Significance**: Positive rearrangement indicates targetable disease, necessitating specialist input. Negative may require follow-up.**Specialist Consultation**: Hematologists should be consulted for management.**Additional Supporting Tests**: NGS, karyotype for confirmation.**Test Limitations**: Detects specific loci; comprehensive approach required.**References**: Indian Journal of Hematology 2024, Eosinophilia Studies India 2023. |
