Fetal-like erythropoiesis frequently accompanies marrow stress conditions such as Diamond-Blackfan syndrome and aplastic anemia. In contrast, patients with transient erythroblastopenia of childhood have erythrocytes which lack fetal characteristics at the time of diagnosis. This report describes nine children with transient erythroblastopenia of childhood in whom transient, fetal-like erythropoiesis was observed during the period of recovery. These patients initially presented with anemia, reticulocytopenia, erythrocytes of normal size for age, low levels of fetal hemoglobin, and i-antigen. During the recovery period, however, erythrocytes manifested one or more fetal characteristics. These included an increased fetal hemoglobin (in three of five patients), the presence of i-antigen (in four of six patients), and macrocytosis (in seven of nine patients). These fetal characteristics persisted more than 2 wk after the reticulocyte count returned to normal. Within one year from diagnosis, red blood cells contained no fetal characteristics.

Speculation: The observations reported here suggest that" fetal-like" red blood cell characteristics may represent a normal response pattern during recovery from marrow hypoplasia. If this hypothesis is correct, similar fetal erythrocyte characteristics should be presentin red blood cells of patients recovering from marrow hypoplasia of various etiologies (eg, hypoplastic crises complicating hemolytic anemias). The great variability in degree and duration o" fetal characteristics" may reflect differences in the regulation of the proliferating erythroid compartment during recovery among individual patients. Although the significance of" fetal-like erythropoiesis" during recovery remains to be defined, it may provideclues to the regulation of hemoglobin synthesis.