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Cytogenetics and FISH negative cryptic acute promyelocytic leukemia with CD56 expression
Jhansi Rani Arumugam1, B K Karthik Bommannan1, Jayachandran Perumal Kalaiyarasi2
1Department of Oncopathology, Cancer Institute (WIA), Adyar, Chennai, Tamil Nadu, India.
Indian Journal of Pathology & Microbiology
|April 14, 2021
Summary
Rare acute promyelocytic leukemia (APL) cases with cryptic PML-RARA insertions, missed by FISH and cytogenetics, were identified using PCR. Early detection ensures favorable prognosis and effective retinoid treatment.
Area of Science:
- Hematology
- Molecular Diagnostics
- Oncology
Background:
- Acute promyelocytic leukemia (APL) typically involves the t(15;17) translocation.
- Prompt diagnosis and treatment of APL lead to a favorable prognosis.
Observation:
- Rare APL cases present with a cryptic insertion of the retinoic acid receptor alpha (RARA) gene into the promyelocytic leukemia (PML) gene.
- This cryptic insertion is undetectable by standard fluorescence in situ hybridization (FISH) and conventional cytogenetics (CC).
Findings:
- Morphology, cytochemistry, and flow cytometry are crucial for initial identification of cryptic APL.
- Polymerase chain reaction (PCR) is the most effective method for detecting these variants, including the PML-RARA fusion.
- The presented case was negative by FISH and CC but positive for PML-RARA via PCR.
Implications:
- Identifying cryptic APL is vital for patient management.
- These APL cases respond well to retinoid therapy.
- Timely diagnosis of cryptic APL ensures a favorable prognosis.
