Optical genome mapping reveals multiple apoptotic and cell-cycle pathway aberrations in B-cell prolymphocytic leukemia: a report of three cases.

B-cell prolymphocytic leukemia (B-PLL) is a rare B-cell neoplasm that presents splenomegaly, lymphocytosis, minimal or absent lymphoadenopathy, at least 55% of prolymphocytes in peripheral blood and a variable clinical course. Complex/composite karyotype and recurrent structural variants (SVs), including TP53 aberrations (mutations/deletion) and MYC abnormalities (translocation or gain) are genetic features typically seen in B-PLL. We applied the genome-wide technology of optical genome mapping (OGM) in 3 cases with B-PLL, finding multiple genomic aberrations, including SVs, copy number variations (CNVs) and aneuploidies. MYC aberrations were not observed in our cases, whereas all B-PLL showed concomitant deletion 17p and TP53 mutations. TP53-disrupted B-PLL cells showed additional genomic alterations that affect genes implicated in extrinsic and intrinsic apoptotic pathways i.e., TNFRSF10, FAS, MDM2, BCL2, and BCL2L11 and genes involved in cell-cycle regulation i.e., IKBKB, CDK2, CDK4, and RB1, suggesting that a convergent multifactorial pathogenetic mechanism may be involved in B-PLL. Applying the OGM technology on cytogenetically complex rare hematological neoplasia may be useful to improve the genetic definition and differential diagnosis of B PLL/SBLPN and related splenic B cell neoplasms.