[Erythroblastopenia in children].

The occurrence of isolated erythroblastopenia is a common problem in paediatrics, and in most cases three diagnoses may be considered: Blackfan-Diamond anaemia (congenital erythroblastopenia), transient erythroblastopenia of childhood and erythroblastopenia consecutive to parvovirus B19 infection. These three diseases have distinctive features: age of onset, association with other laboratory and clinical abnormalities and above all, transient or chronic character are of assistance in making an exact diagnosis. The mechanisms responsible for Blackfan-Diamond anaemia and transient erythroblastopenia are imperfectly known. In vitro studies of the properties of erythroblast progenitors suggest intrinsic damage to these cells, whereas in transient erythroblastopenia their differentiation seems to be inhibited, perhaps by an immune mechanism. In both cases, the abnormality has not be identified. The selective tropism of parvovirus B19 towards actively dividing erythroblasts accounts for the acute erythroblastopenia observed in a context of chronic haemolysis. The responsibility of parvovirus B19 in chronic or relapsing erythroblastopenia in immunocompromised patients is a recent discovery. In view of the protean haematological pathology in this context and of the difficult therapeutic problems it creates, this diagnosis must systematically be envisaged, notably in children under chemotherapy.