Isolated deletion of the long arm of chromosome 20 [del(20q12)] in myelodysplastic syndrome: a case report and literature review

Prognostic classification of MDS is improved by the inclusion of FISH panel testing with conventional cytogenetics

Cytogenetics is a critical independent prognostic factor in myelodysplastic syndromes (MDS). Conventional cytogenetics (CC) and Fluorescence in situ hybridization (FISH) Panel Testing are extensively used for the prognostic stratification of MDS, although the FISH test is not yet a bona fide component of the International Prognostic Scoring System (IPSS). The present study compares the utility of CC and FISH to detect chromosomal anomalies and in prognostic categorization. GTG-Banding and FISH Panel Testing specifically for -5/-5q, -7/-7q, +8 and -20q was performed on whole blood or bone marrow samples from 136 patients with MDS. Chromosomal anomalies were found in 40 cases by CC, including three novel translocations. FISH identified at least one anomaly in 54/136 (39.7%) cases. More than one anomaly was found in 18/54 (33.3%) cases, therefore, overall FISH identified 75 anomalies of which 32 (42.6%) were undetected by CC. FISH provided additional information in cases with CC failure and in cases with a normal karyotype. Further, in ten cases with an abnormal karyotype, FISH could identify additional anomalies, increasing the number of abnormalities per patient. Although CC is the gold standard in the cytogenetic profiling of MDS, FISH has proven to be an asset in identifying additional abnormalities. The number of anomalies per patient can predict the prognosis in MDS and hence, FISH contributed towards prognostic re-categorization. The FISH Panel testing should be used as an adjunct to CC, irrespective of the adequacy of the number of metaphases in CC, as it improves the prognostic classification of MDS.

Refractory thrombocytopenia and neutropenia: a diagnostic challenge

The 2008 WHO classification identified refractory cytopenia with unilineage dysplasia (RCUD) as a composite entity encompassing refractory anemia, refractory thrombocytopenia (RT), and refractory neutropenia (RN), characterized by 10% or more dysplastic cells in the bone marrow respective lineage. The diagnosis of RT and RN is complicated by several factors. Diagnosing RT first requires exclusion of familial thrombocytopenia, chronic auto-immune thrombocytopenia, concomitant medications, viral infections, or hypersplenism. Diagnosis of RN should also be made after ruling out differential diagnoses such as ethnic or familial neutropenia, as well as acquired, drug-induced, infection-related or malignancy-related neutropenia. An accurate quantification of dysplasia should be performed in order to distinguish RT or RN from the provisional entity named idiopathic cytopenia of unknown significance (ICUS). Cytogenetic analysis, and possibly in the future somatic mutation analysis (of genes most frequently mutated in MDS), and flow cytometry analysis aberrant antigen expression on myeloid cells may help in this differential diagnosis. Importantly, we and others found that, while isolated neutropenia and thrombocytopenia are not rare in MDS, those patients can generally be classified (according to WHO 2008 classification) as refractory cytopenia with multilineage dysplasia or refractory anemia with excess blasts, while RT and RN (according to WHO 2008) are quite rare. These results suggest in particular that identification of RT and RN as distinct entities could be reconsidered in future WHO classification updates.