Bone marrow histology and CD34 immunostaining in the prognostic evaluation of primary myelodysplastic syndromes

The prognostic impact of bone marrow biopsy (BMB) histology and CD34 immunoreactivity was compared with that of the more conventional parameters (the FAB diagnosis, peripheral blood values, percentage of BM blasts and some common prognostic scores) in 100 MDS patients. Statistical correlations among the cytological, haematological, histological and immunohistochemical parameters and their relationship with clinical outcome were searched for. At univariate analysis, FAB classification (P < 0.001), pattern of blastic infiltration at BMB (P < 0.005), presence of CD34(+) aggregates (P < 0.0005), percentage of blasts in BM aspirate (P < 0.0001) and percentage of CD34 positivity (P < 0.0001) proved to be linked to leukaemic transformation and, except for FAB classification, retained a high degree of prognostic significance in terms of survival. Leukaemic transformation occurred in 16/18 patients simultaneously presenting 'large' blastic infiltrates at BMB and CD34(+) aggregates (P < 0.00001); 9/17 evaluable patients died within 12 months of diagnosis (P < 0.001). Discriminant functions for leukaemic transformation and survival did not offer any advantage over univariate analysis in the prognostic work-up. The results indicate that the size of blastic aggregates and CD34 positivity allowed patients with a worse prognosis to be identified irrespective of their FAB subtype, but the prognostic impact is considerably greater when both parameters are simultaneously taken into account, as testified by the restricted and homogenous subgroup of patients with both 'large' and CD34-positive aggregates.