Clinical and genetic characterization of de novo double-hit B cell precursor leukemia/lymphoma

How Many Tests Does It Take to Diagnose a Triple-Hit B-Lymphoblastic Lymphoma? (Hint, It's A Lot)

B-lymphoblastic leukemia/lymphoma (B-ALL/LBL) is a precursor B-cell neoplasm that often harbors specific cytogenetic/molecular abnormalities with distinctive clinical, phenotypic, and prognostic characteristics. Subcategorization of B-ALL/LBL therefore requires extensive cytogenetic and/or molecular testing to determine the appropriate classification and therapeutic interventions for these patients. Herein, we present a case of a 17-year-old young woman diagnosed with B-LBL harboring not only an IGH::MYC rearrangement but also BCL2 and BCL6 rearrangements (so-called "triple-hit") and somatic biallelic TP53 inactivation. MYC rearrangements are relatively rare in B-ALL/LBL, and the identification of a "triple-hit" elicited an initial diagnostic dilemma. However, a multimodal approach allowed for the classification of this complex case and helped guide selection of an appropriate therapeutic regimen.

Emerging molecular subtypes and therapies in acute lymphoblastic leukemia

Tremendous strides have been made in the molecular and cytogenetic classification of acute lymphoblastic leukemia based on gene expression profiling data, leading to an expansion of entities in the recent International Consensus Classification (ICC) of myeloid neoplasms and acute leukemias and 2022 WHO Classification of Tumours: Haematolymphoid Tumors, 5th edition. This increased diagnostic and therapeutic complexity can be overwhelming, and this review compares nomenclature differences between the ICC and WHO 5th edition publications, compiles key features of each entity, and provides a diagnostic algorithmic approach. In covering B-lymphoblastic leukemia (B-ALL), we divided the entities into established (those present in the revised 4th edition WHO) and novel (those added to either the ICC or WHO 5th edition) groups. The established B-ALL entities include B-ALL with BCR::ABL1 fusion, BCR::ABL1-like features, KMT2A rearrangement, ETV6::RUNX1 rearrangement, high hyperdiploidy, hypodiploidy (focusing on near haploid and low hypodiploid), IGH::IL3 rearrangement, TCF3::PBX1 rearrangement, and iAMP21. The novel B-ALL entities include B-ALL with MYC rearrangement; DUX4 rearrangement; MEF2D rearrangement; ZNF384 or ZNF362 rearrangement, NUTM1 rearrangement; HLF rearrangement; UBTF::ATXN7L3/PAN3,CDX2; mutated IKZF1 N159Y; mutated PAX5 P80R; ETV6::RUNX1-like features; PAX5 alteration; mutated ZEB2 (p.H1038R)/IGH::CEBPE; ZNF384 rearranged-like; KMT2A-rearranged-like; and CRLF2 rearrangement (non-Ph-like). Classification of T-ALL is complex with some variability in how the subtypes are defined in recent literature. It was classified as early T-precursor lymphoblastic leukemia/lymphoma and T-ALL, NOS in the WHO revised 4th edition and WHO 5th edition. The ICC added an entity into early T-cell precursor ALL, BCL11B-activated, and also added provisional entities subclassified based on transcription factor families that are aberrantly activated.

B-cell acute lymphoblastic leukaemia: recent discoveries in molecular pathology, their prognostic significance, and a review of the current classification

Acute lymphoblastic leukaemia (ALL) remains a leading cause of non-traumatic death in children, and the majority of adults diagnosed will succumb to the disease. Recent advances in molecular biology and bioinformatics have enabled more detailed genomic analysis and a better understanding of the molecular biology of ALL. A number of recurrent genomic drivers have recently been described, which not only aid in diagnosis and prognostication, but also may offer opportunities for specific therapeutic targeting. The present review summarises B-ALL genomic pathology at diagnosis, including lesions detectable using traditional cytogenetic methods as well as those detected only through advanced molecular techniques.

De novo double-hit B-cell precursor leukemia/lymphoma - an unusual presentation as peritoneal lymphomatosis

Peritoneal lymphomatosis (PL) is a rare presentation of extranodal precursor leukemia/lymphoma. The presentation is often non-specific, leading to delayed diagnosis and treatment. In this case, though the preliminary diagnosis was established on ascitic fluid cytology, the disease progressed rapidly, leading to demise before initiating chemotherapy. Immunophenotyping and molecular studies, performed later, established a diagnosis of de novo B-cell precursor leukemia/lymphoma with MYC, BCL2 rearrangements (Double-hit lymphoma). MYC, BCL2 rearrangements are rarely reported in precursor B-lymphoma/leukemia which carry dismal prognosis. In this report, we illustrate autopsy findings of PL in an elderly gentleman who presented with ascites for evaluation.