De novo myelodysplastic syndrome (MDS) with deletion of the long arm of chromosome 20: A subtype of MDS with distinct hematological and prognostic features?

We report on 8 cases of de novo myelodysplastic syndromes (MDS) with deletion of the long arm of chromosome 20 (del 20q), who represented about 2% (8/392) of our cases of de novo MDS with cytogenetic analysis seen during a period of 9 yr. Median age was 69 yr, and there were 7 males and 1 female. Anemia was absent or very mild (Hb > 11 g/dl) in 5 patients. Only 1 patient had neutrophils < 0.5 x 10(9)/l, and none had platelets < 50 x 10(9)/l. Four patients had refractory anemia (RA), 2 had refractory anemia with ringed sideroblasts (RARS), and 2 had refractory anemia with excess of blasts (RAEB). Del 20q was isolated in 5 patients, and associated with other chromosomal rearrangement(s) in 3 patients. Only 1 patient progressed to ANLL and 2 showed an increase in bone marrow blasts during evolution. The 5 other patients had stable disease after 18-77 months. By comparison with de novo MDS patients with other cytogenetic findings, patients with del 20q had a tendency towards lower incidence of anemia and excess of marrow blasts, lower incidence of progression to AML and more prolonged survival, although differences were not significant. Only patients with isolated del 5q had a more prolonged survival than patients with del 20q.