Deletion (20q) as the sole abnormality in Waldenstrِm macroglobulinemia suggests distinct pathogenesis of 20q11 anomaly

The deletion of the long arm of chromosome 20, or del(20q), is a common cytogenetic abnormality in various myeloid disorders but is less commonly seen in lymphoid neoplasms. Here we report a case of Waldenström macroglobulinemia with del(20q) as the sole cytogenetic anomaly. No translocation including immunoglobulin genes was identified by spectral karyotyping (SKY) analysis. Reviewing all 11 reported cases of plasma cell dyscrasia possessing sole del(20q), including our case, none of 4 cases with del(20q) as an initial anomaly developed myelodysplastic syndrome–acute myeloid leukemia (MDS/AML), but at least 3 cases with del(20q) appearing after chemotherapy developed MDS/AML at or after the time of del(20q). We propose that the del(20q) may have different clinical significance in plasma cell dyscrasia: one is when del(20q) appears at diagnosis and may involve the initial event of oncogenesis, and the other is when del(20q) appears after treatment and is associated with therapy-related and potential MDS/AML risk.