Isodicentric (X)(q13) in haematological malignancies: presentation of five new cases, application of fluorescence in situ hybridization (FISH) and review of the literature.

Idic(X)(q13) represents a rare but recurrent chromosomal abnormality in haematological malignancies. We present five new cases characterized by this particular aberration and review the literature on this subject. The patients were elderly females with a diagnosis of refractory anaemia (1/5), refractory anaemia with ringed sideroblasts (2/5), chronic myelomonocytic leukaemia (1/5), and Philadelphia chromosome-negative chronic myeloid leukaemia (1/5). Three out of the five patients demonstrated an increased proportion of bone marrow ringed sideroblasts. After a follow-up period of 30-57 months all patients but one are alive. Idic(X)(q13) always occurred as the sole chromosomal abnormality, either in one or in two copies. We confirmed the dicentric nature of the aberration by fluorescence in situ hybridization (FISH) on metaphases as well as interphase nuclei using an X-chromosome-specific alpha-satellite probe, and performed chromosome painting to visualize possible additional chromosomal changes involving the X chromosomes. Our findings and the data of 17 previously published cases indicate that idic(X)(q13): (1) may play a significant pathogenetic role in haematological malignancies affecting exclusively females and deriving predominantly from early progenitor cells; (2) is frequently associated with a pathological iron accumulation; (3) indicates a variable prognosis.