Cytogenetics and FISH negative cryptic acute promyelocytic leukemia with CD56 expression

Acute promyelocytic leukemia (APL) is characterized by reciprocal translocation t(15;17)(q22;q21) and has a favorable prognosis upon immediate recognition and treatment. However, rare cases of APL show a cryptic insertion of retinoic acid receptor alpha (RARA) gene into promyelocytic leukemia (PML) gene which is negative both by fluorescence in situ hybridization (FISH) and conventional cytogenetics (CC). Morphology, cytochemistry and flow cytometry play a key role in early identification of such cases. Polymerase chain reaction (PCR) remains the most efficient diagnostic modality for detection of cryptic APL and other variants. It is important to identify these cases as they show beneficial response to retinoids and favourable prognosis. We herein present a rare case of cryptic APL negative by FISH and conventional cytogenetics but positive for PML-RARA by PCR.

CD19 negative and dim precursor B-lineage acute lymphoblastic leukemias: real-world challenges in a targeted-immunotherapy era

Flow cytometric diagnosis and minimal residual disease (MRD) assessment of precursor B-lineage acute lymphoblastic leukemia (B-ALL) are heavily dependent on CD19 based gating strategies. However, this approach is not optimal in the diagnosis and follow-up of CD19 negative or dim B-ALLs. Though CD19 negative B-ALLs are rare, in the current era of CD19 targeted immuno-therapy, CD19 negative B-ALL relapses are frequent. We have presented our cohort of 14 de novo CD19 negative and dim B-ALLs and have highlighted the difficulties faced during diagnosis and MRD assessment of these patients. We have also discussed the need to identify alternative B-lineage gating markers and strategies to deal with such scenarios.