Der(20)idic(20)(p11)del(20)(q11q13) Is Seen Not Only in Myeloid Disorders but Also in Lymphoid Disorders: A Report of Further Seven Cases.

As a newly identified cytogenetic abnormality, idic(20q−) has been reported in thirteen cases of myelodysplastic syndrome (MDS), one case of chronic myelomonocytic leukemia, and one case of acute myeloid leukemia (AML) since 2004. Here we report additional seven cases consisting of 3 MDS, 2 AML and 2 acute lymphocytic leukemia (ALL). A karyotype analysis using R-banding technique revealed an i(20q−) as a sole anomaly in 5 of them and as a secondary change in other 2 cases: one was a B-cell ALL whose leukemic cells at presentation had a karyotype of 45, XY, dic(9;20)(p11;q11). However, an idic(20q−) was found coexistent with the dic(9;20) as relapse; another was a Ph positive ALL whose leukemic cells simultaneously contained t(9;22)(q34;q11) and idic(20q−). A series of FISH using multiple probes such as the centromeric probes specific for chromosomes 9 and 20, the subtelomeric probe for 20q, the locus-specific probe for 20q12, the whole chromosome paint probes for chromosomes 9 and 22 and the translocation probe for t(9;22) demonstrated the idic(20q−) to be actually a der(20)idic(20)(p11)del(20)(q11q13), confirmed the dic(9;20)(p11;q11) in case 6 and revealed a BCR/ABL fusion gene in case 7. Among them, 2 MDS patients survived and anemic except one lost to follow-up, 2 AML and 2 ALL patients did not obtain complete remission and died with short survivals. Our study brings the total number of cases with idic(20q−) to 22 and suggests that the disease spectrum of idic(20q−) is not restricted to myeloid disorders, and it also includes ALL.