In order to characterize these lymphomas in children from the United States, IRF4 FISH and immunohistochemical stains were performed on 32 follicular lymphoma and diffuse large B-cell lymphoma (DLBCL) from Children's Oncology Group studies.
CD10 expression was significantly reduced in BCL2-breakpoint-negative FLs of all stages and MUM1 and Ki67 expression were significantly increased in BCL2-break-negative early-stage FLs.
We applied array-comparative genomic hybridization and molecular inversion probe assay analyses to formalin-fixed paraffin-embedded tissues from 18 patients aged 18 years and under with IRF4 translocation negative follicular lymphoma.All evaluable cases lacked t(14;18).
Gene expression analysis revealed increased expression of MAPK1, AKT1, PRKCE, IL4R and DROSHA and decreased expression of CDKN1A/p21, SOCS2, CHEK1, RAD51, KLF4, BLIMP1 and IRF4 in follicular lymphoma.
The analysis suggests that MUM1 expression dichotomises FL into low-grade FL of CD10+/Bcl-6+/MUM1-/Ki-67low phenotype, and high-grade FL of CD10+/- /Bcl-6+/weak/MUM1+/ Ki-67high phenotype.
The analysis suggests that MUM1 expression dichotomises FL into low-grade FL of CD10+/Bcl-6+/MUM1-/Ki-67low phenotype, and high-grade FL of CD10+/- /Bcl-6+/weak/MUM1+/ Ki-67high phenotype.
In B cell non-Hodgkin's lymphoma (NHL), MUM1 expression was observed in 73.2% (30/41) of diffuse large B cell lymphoma (DLBCL), 20% (1/5) of marginal zone lymphoma (MZL) and 43% (3/7) of small lymphocytic lymphoma (SLL) cases, whereas it was not seen in any cases of mantle cell lymphoma (MCL) or follicle center lymphoma (FCL).