Hypoplastic myelodysplastic syndrome (h-MDS) is a distinctive clinical entity with poorer prognosis and frequent karyotypic and FISH abnormalities compared to aplastic anemia (AA)

The aims of the present study are two-fold: (1) to define the clinical features of hypoplastic myelodysplastic syndrome (h-MDS) in comparison with aplastic anemia (AA) and (2) to evaluate the prognostic roles of karyotyping and fluorescent in situ hybridization (FISH) in these hypoplastic marrow syndromes.Based on a medical record review at Seoul National University Hospital, the records of 409 patients diagnosed with either h-MDS or AA were evaluated. Of these patients, 358 had been diagnosed with AA and 51 with h-MDS (median age, 39 years). At diagnosis, 235 and 165 patients underwent karyotyping and FISH analysis, respectively. Karyotypic abnormalities and trisomy 8 and trisomy 1q FISH abnormalities were found more frequently in h-MDS patients than in AA patients. Median overall survival (OS) of h-MDS patients was shorter than that of AA patients (83 vs. 201 months, P = 0.007), with the OS of h-MDS patients falling between that of severe and very severe AA patients. Patients with h-MDS had more frequent leukemic conversion (P < 0.001) than did AA patients. In AA patients, karyotypic abnormality was not prognostic (P = 0.646), while in h-MDS patients, abnormalities in trisomy 1q FISH (P = 0.002) and in 20q deletion FISH (P = 0.005) were predictive of poor prognosis.In conclusion, the prognosis for h-MDS patients falls between that of severe and very severe AA patients. Moreover, h-MDS is frequently accompanied by karyotypic and FISH abnormalities and is prone to leukemic conversion. Trisomy 1q and 20q deletion FISH abnormalities may have important prognostic roles in patients with h-MDS.