Therapy-related myeloid neoplasms with isolated del(20q): comparison with cases of de novo myelodysplastic syndrome with del(20q)

The isolated deletion of chromosome 20q [del(20q)] has been observed in both de novo and therapy-related cases of myelodysplastic syndrome (MDS). The clinicopathologic features of de novo MDS with isolated del(20q) are well characterized. However, relatively little is known about therapy-related myeloid neoplasms (t-MNs) with isolated del(20q). In this study, we identified five cases of t-MN and 26 cases of de novo MDS with isolated del(20q) over a 10-year period. All cases had a long latency interval from the treatment of the primary malignancy to the onset of t-MN, and all were associated with frequent bone marrow dysplasia. The del(20q) was the sole abnormality detected at the time of diagnosis of t-MN in three cases, six years prior to diagnosis in one case, and at the time of relapse of acute myeloid leukemia (AML) in one case. Three patients with therapy-related MDS (t-MDS) had a relatively indolent clinical course, whereas two patients presented with AML or developed AML shortly after t-MDS. The patients with de novo MDS with isolated del(20q) presented frequently with anemia and thrombocytopenia which were associated with bone marrow dysplasia. The median overall survival was 64 months. In all cases, del(20q) was present at the time of diagnosis.