Features of Pediatric B-lymphoblastic lymphoma with KMT2A rearrangements in the German NHL-BFM Group

Abstract

KMT2A rearrangements in precursor B-cell neoplasms are common in children and has poor prognosis. However, reports on KMT2A were on pediatric B-lymphoblastic leukemia (pB-ALL), while genetic studies on pediatric Blymphoblastic lymphoma (pB-LBL) are limited. To study this entity, we constructed tissue microarrays from paraffin blocks of 64 patients <18 years of age with pB-LBL from 1996 to 2017 from the Kiel Lymph Node Registry, and performed FISH using KMT2A break-apart probes. 12 of these patients (19%) have KMT2A rearrangement, more frequent than that in pB-ALL. The mean age is 5.4 years (range 0.7 to 17), older than those with KMT2A-positive pBALL. The most frequent translocation in pB-LBL is t(11;19), while none of the cases had t(4;11), the commonest finding in pB-ALL. Our findings suggest that pediatric pB-LBL may be genetically different from pB-ALL, as they contain genetic subgroups at a different frequency. Moreover, we present an example that clinical features of a subgroup differ between lymphoma and leukemia.