Chapter 444 Acquired Pure Red Blood Cell Anemia
Transient Erythroblastopenia of Childhood
The temporary suppression of erythropoiesis results in reticulocytopenia and moderate to severe normocytic anemia. Some degree of neutropenia occurs in up to 20% of cases. Platelet numbers are normal or elevated. Similar to the situation observed in iron-deficiency anemia and other red blood cell (RBC) hypoplasias, thrombocytosis is presumably caused by increased erythropoietin, which has some homology with thrombopoietin. Mean corpuscular volume (MCV) is characteristically normal for age, and fetal hemoglobin (HbF) levels are normal before the recovery phase. RBC adenosine deaminase (ADA) levels are normal in this disorder, thus contrasting with the elevation noted in most cases of congenital hypoplastic anemia (Table 444-1). Differentiation from the latter disease is sometimes difficult, but differences in age at onset and in age-related MCV, HbF, and ADA are usually helpful. The peak occurrence of TEC coincides with that of iron-deficiency anemia in infants receiving milk as their main caloric source; differences in MCV should help to distinguish between these 2 disorders.
Table 444-1 COMPARISON OF DIAMOND-BLACKFAN ANEMIA AND TRANSIENT ERYTHROBLASTOPENIA OF CHILDHOOD
FEATURE | DBA | TEC |
---|---|---|
Male : female | 1.1 | 1.3 |
Age at diagnosis, male (mo) | ||
Mean | 10 | 26 |
Median | 2 | 23 |
Range | 0-408 | 1-120 |
Age at diagnosis, female (mo) | ||
Mean | 14 | 26 |
Median | 3 | 23 |
Range | 0-768 | 1-192 |
Boys >1 yr | 9% | 82% |
Girls >1 yr | 12% | 80% |
Etiology | Genetic | Acquired |
Antecedent history | None | Viral illness |
Physical examination abnormal | 25% | 0% |
Laboratory | ||
Hemoglobin (g/dL) | 1.2-14.8 | 2.2-12.5 |
WBCs <5,000/µL | 15% | 20% |
Platelets >400,000/µL | 20% | 45% |
Adenosine deaminase | Increased | Normal |
MCV increased at diagnosis | 80% | 5% |
MCV increased during recovery | 100% | 90% |
MCV increased in remission | 100% | 0% |
HbF increased at diagnosis | 100% | 20% |
HbF increased during recovery | 100% | 100% |
HbF increased in remission | 85% | 0% |
i Antigen increased | 100% | 20% |
i Antigen increased during recovery | 100% | 60% |
i Antigen increased in remission | 90% | 0% |
DBA, Diamond-Blackfan anemia; HbF, fetal hemoglobin; MCV, mean cell volume; TEC, transient erythroblastopenia of childhood; WBC, white blood cell.
From Nathan DG, Orkin SH, Ginsburg D, et al, editors: Nathan and Oski’s hematology of infancy and childhood, ed 6, vol 1, Philadelphia, 2003, WB Saunders, p 329. Adapted from Alter BP: The bone marrow failure syndromes. In Nathan DG, Oski FA, editors: Hematology of infancy and childhood, ed 3, Philadelphia, 1987, WB Saunders, p 159; and Link MP, Alter BP: Fetal erythropoiesis during recovery from transient erythroblastopenia of childhood (TEC), Pediatr Res 15:1036–1039, 1981.
Red Cell Aplasia Associated with Parvovirus B19 Infection
Parvovirus B19 is a common infectious agent that causes erythema infectiosum (fifth disease) (Chapter 243). It is also the best-documented viral cause of RBC aplasia in patients with chronic hemolysis, patients who are immunocompromised, and fetuses in utero. The virus is particularly infective and cytotoxic in marrow erythroid progenitor cells, interacting specifically with the RBC P antigen. In addition to decreased or absent erythroid precursors, characteristic nuclear inclusions in erythroblasts and giant pronormoblasts may be seen under the light microscope in bone marrow specimens.
Miscarriage and Hydrops Fetalis
Parvovirus infection and destruction of erythroid precursors can also occur in utero. Such events are associated with increased fetal wastage in the first and second trimesters. Infants may be born with hydrops fetalis (Chapter 97) and viremia. The presence of persistent congenital parvovirus infection is detected by PCR of peripheral blood and/or bone marrow DNA, because immunologic tolerance to the virus can prevent the usual development of specific antibodies.
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