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.
Keywords: Isolated 20q-; Isolated i(20q-); Morphological dysplasia; Myelodysplastic syndrome.