B-Lymphoblastic Leukemia in Patients With Chronic Lymphocytic Leukemia

Abstract

Our data suggest that at least some cases of B-LBL arising in patients with CLL are independent, secondary neoplasms rather than a manifestation of histologic transformation.

Shared clonal IGH rearrangement in BCP‐ALL occurring after CLL: pitfalls and implications for MRD monitoring

“…The onset of BCP‐ALL after CLL is rarely described and its pathogenesis remains unclear. While IGH clonally related BCP‐ALL cases were reported after treatment for CLL, 5,7 in other reports, both malignancies were clonally unrelated 4,6 . In our present observation, the identical clonal IGH rearrangement suggests that BCP‐ALL represent a blastic transformation of CLL, emerging from an IGH VDJ‐ rearranged progenitor present at CLL diagnosis that then acquired an AFF1‐KMT2A fusion as a blastic oncogenic event.…”

“…These are mainly represented by acute myeloid leukaemia (AML) and myelodysplastic syndromes, a World Health Organization (WHO)‐recognised entity, reaching 5% following purine analogue‐based chemo‐immunotherapy 1–3 . Conversely, B‐cell precursor acute lymphoblastic leukaemia (BCP‐ALL) is uncommon after CLL (<1%), occurs after treatment but also in untreated patients and a clonal relationship is established in some reports, highlighting that pathogenesis of BCP‐ALL in the CLL setting is still unclear 4–7 …”

Histologic transformation of chronic lymphocytic leukemia/small lymphocytic lymphoma

“…Most patients are men, with a reported age range of 42-76 years. The reported interval between CLL/SLL diagnosis and RS-LBL ranges from 2 months to 7 years; although simultaneous presentation of CLL/SLL and RS-LBL may occur [49][50][51][52][53][54][55][56][57]. RS-LBL is characterized by numerous lymphoblasts in a background of cells typical of CLL/SLL.…”

“…The blasts are intermediate size, with indented nuclei, fine chromatin, one or two small nucleoli, and scant cytoplasm. The neoplastic cells express HLA-DR, surface Ig, pan-B cell markers, and TdT [51,52,[55][56][57]; a TdT-negative case also has been reported [54]. There is variable expression of CD5, CD10, CD22, and CD23 [51,52,[54][55][56][57].…”

“…These data suggest that B-LBL can occur in patients with CLL/SLL associated with either mutated or unmutated IGHV. Furthermore, the authors suggested that B-LBL may represent a secondary neoplasm and not evidence of histologic transformation in a subset of patients [56]. Cytogenetic studies also have shown the presence of 8q24 translocation acquired at the time of transformation to B-LBL in some patients [51,52].…”