TRANSIENT ERYTHROBLASTOPENIA OF CHILDHOOD (TEC)
Transient erythroblastopenia of childhood (TEC) is an acute, self-limiting anemia that affects children between one month and 6 years of age. Children usually present with pallor and symptoms of anemia, although the finding of anemia may be incidental. TEC is characterized by a normocytic, normochromic anemia and reticulocytopenia (< 2%). An absolute neutropenia may also be observed in some patients. Bone marrow examination is not usually required for diagnosis.
Examination of the bone marrow in patients with TEC demonstrates normocellular marrow with erythroid hypoplasia. Maturation arrest at the pronormoblast stage is typical, although complete absence of erythroid precursors may also be seen. The myeloid: erythroid ratio is markedly increased. No abnormality of the lymphocyte population should be identified on flow cytometric evaluation. Transfusion support may be required in some cases. Patients usually recover in 4 to 8 weeks, although recovery can take up to 1 year.
The etiology of TEC has not been clearly identified. Although patients often have a preceding viral illness, and a number of viruses have been found in patients with TEC, no definite association with a particular virus has been established. Immune pathways, including IgG and IgM mediated pathways and cell-mediated immunity, are thought to play a role in the pathogenesis of TEC. The primary differential diagnosis is Diamond-Blackfan anemia, although infection with parvovirus B19 should be considered in children with chronic hemolytic anemias.
Diamond-Blackfan anemia (DBA) usually presents in infancy and is characterized by a complete absence of erythropoietic precursors in the bone marrow. It presents with a profound macrocytic anemia which is accompanied by congenital malformations in approximately half of cases. DBA is caused by mutations in the genes that encode the ribosomal proteins. The clinical manifestations vary widely, and the anemia may be steroid responsive or cured only by stem cell transplantation.
Parvovirus B19 selectively invades erythroid precursors, leading to a pure red cell aplasia. In immunocompetent children, it is usually associated with erythema infectiosum and a transient drop in hemoglobin of about 1 g/dL. However, children with a chronic hemolytic anemia may experience an aplastic crisis due to the shortened life span of their red blood cells and a temporary inability to produce new erythrocytes. If bone marrow evaluation is performed, the marrow may demonstrate giant pronormoblasts with intranuclear viral inclusions. PCR for parvovirus will be positive in these cases.
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Contributed by Alicia Hunt, MD and Grant Bullock, MD, PhD