Isoderivative chromosome 20 in bone marrow: three new cases

Retrospective evaluation of bone marrow cell morphology in a cohort of patients with isolated idic(20q-) karyotypic abnormalities

Isochromosome 20q- (i(20q-)), as a rare reproducible chromosomal anomaly formed on the basis of 20q-, has not been commonly reported. Due to the rarity of this karyotypic anomaly, the bone marrow morphological characteristics of the patients with i(20q-) have not been clarified until now. In this study, the bone marrow cell morphology from MDS patients with isolated i(20q-), isolated 20q-, and normal karyotype was retrospectively compared and statistically analyzed. The results indicated that the isolated i(20q-) was mostly detected in MDS-MLD patients. The frequency and proportion dysplasia of cytoplasmic vacuolization in erythoid cells and small or unusually large size in myeloid cells of isolated i(20q-) MDS patients were significantly higher than those of normal karyotype MDS patients respectively (P < 0.05); the frequency and proportion dysplasia of decreased granules/agranularity in myeloid cells of isolated i(20q-) MDS patients were higher than those of isolated 20q- MDS patients (P < 0.05). The incidence of some specific morphological manifestations, such as deeply lobulated and hyperlobulated megakaryocytes and hypogranular and vacuolized eosinophils, may be an important morphological implication for the anomaly of isolated i(20q-). These morphological features of dysplasia may be helpful in distinguishing MDS with isolated i(20q-) from those with isolated 20q- and normal karyotype.

Investigation of 305 patients with myelodysplastic syndromes and 20q deletion for associated cytogenetic and molecular genetic lesions and their prognostic impact

In patients with myelodysplastic syndromes (MDS), sole 20q deletion [del(20q)] is a recurrent favourable abnormality. We studied additional molecular and cytogenetic lesions and their prognostic impact in 305 MDS patients with del(20q) (229 males/76 females; 29-90 years). All patients were investigated by cytomorphology and chromosome banding analysis (CBA), subsets by fluorescence in situ hybridization, molecular mutation screening, and array comparative genomic hybridization (aCGH). By aCGH (n = 30), the minimal common deleted region (CDR) was flanked by PTPRT (20q13·11) and EYA2 (20q13·12). 210 (68·9%) patients had 'early MDS' without blast increase, 95 (31·1%) 'advanced' MDS with blast increase (5-19%). Additional chromosomal abnormalities (ACAs) were detected in 88/305 (28·9%) patients. Patients with advanced MDS more frequently had ACAs (P = 0·003) and had a higher mean number of ACAs (P = 0·020) and of molecular mutations (P = 0·060). Spliceosome mutations were frequent (U2AF1: n = 31/155; 20·0%; SRSF2: n = 31/159; 19·5%; SF3B1mut: n = 8/159; 5·0%). ASXL1mut (25/153; 16·3%) were associated with advanced MDS (P = 0·001). Presence of ≥3 ACAs (P = 0·003) and ASXL1mut (P = 0·002) were associated with worse 2-year survival. In conclusion, the cytogenetic subgroup of MDS with del(20q) has a good prognosis but may be further subclassified by additional cytogenetic and molecular lesions. U2AF1mut is overrepresented in MDS with del(20q), and ASXL1mut is prognostically adverse.

Morphology, cytogenetics, and survival in myelodysplasia with del(20q) or ider(20q): a multicenter study

Isochromosome of the long arm of chromosome 20 with interstitial loss of material [ider(20q)] is a rare cytogenetic abnormality reported in myelodysplastic syndrome (MDS), with neither specific morphological pattern nor clear prognostic significance. The aim of this retrospective multicentric study is to compare the peripheral blood and bone marrow morphology of MDS patients with ider(20q) (n = 13) and del(20q) (n = 21) and controls (n = 47) in order to investigate whether the ider(20q) harbors specific morphological features. The secondary objective is to compare the outcome of patients from both groups. This study performed on the largest cohort of MDS patients with ider(20q) is the first that identifies specific morphological features (hypogranulated and vacuolized neutrophils and neutrophil erythrophagocytosis) allowing the identification of this cytogenetic abnormality with high sensitivity (70%) and specificity (85.7%). Suspected ider(20q) by morphology should therefore support targeted FISH tests in case of non informative karyotype. This combined approach will allow a better estimation of the prevalence of this underdiagnozed entity. The overall survival and progression-free survival did not statistically differ in both groups. However, hypogranulated and vacuolized neutrophils were significantly associated with survival.