Patients with a history of chemotherapy and isolated del(20q) with minimal myelodysplasia have an indolent course

Objectives: Isolated deletion (20_q) is relatively common in myeloid neoplasms and has been rarely reported in cases of therapy-related myelodysplastic syndrome (MDS). Our aim was to characterize cases of isolated del(20_q) in bone marrow biopsy specimens from patients with a history of chemotherapy with morphologic findings insufficient for a diagnosis of MDS. Methods: In this retrospective study from one institution, we identified 22 patients with isolated del(20_q) and no or minimal dysplasia and evaluated clinical and pathologic characteristics. Results: Eleven of the patients had a history of chemotherapy for mostly lymphoproliferative disorders. There were no statistically significant differences in peripheral blood or bone marrow features between patients with a history of chemotherapy and those without. Three patients with a history of chemotherapy had died at last follow-up; cause of death was recurrent nonmyeloid neoplasm. None of the patients with a history of chemotherapy subsequently developed a high-grade myeloid neoplasm, whereas one of the patients who had not received prior chemotherapy developed refractory anemia with excess blasts 2. Conclusions: The presence of del(20_q) as an isolated bone marrow cytogenetic abnormality in the absence of morphologic findings sufficient for a diagnosis of acute myeloid leukemia, myeloproliferative neoplasm, or MDS portends an indolent clinical course, regardless of previous exposure to chemotherapy.