F-blast is a useful marker for differentiating hypocellular refractory anemia from aplastic anemia.

Making a morphologic distinction between hypocellular refractory anemia (hypo RA) and aplastic anemia (AA) is difficult. To investigate the significance of hemoglobin F-containing erythroblasts (F-blasts) and p53 expression in making the distinction between hypo RA and acquired AA, we immunohistochemically assessed F-blasts and p53 in bone marrow specimens from 16 patients with hypo RA, 31 patients with acquired AA, and 15 hematologically normal individuals. F-blast production was elevated in 87.5% (14/16) of patients with hypo RA, but in only 3.2% (1/31) of patients with AA (P < .01). p53 was overexpressed in 75.0% (12/16) of hypo RA patients and in 6.4% (2/31) of AA patients (P < .01). The mean contents of F-blasts and p53-positive cells in patients with hypo RA were 6.31% +/- 3.27% and 7.54% +/- 4.36%, respectively, of all bone marrow cells, which were significantly higher than for patients with AA (0.35% +/- 0.46% and 0.58% +/- 1.29%, P < .01). In conclusion, a high prevalence of elevated F-blast production is noted in hypo RA, suggesting that the assessment of F-blasts in bone marrow can be used as an additional tool for differentiating hypo RA from acquired AA.