Pure red cell aplasia (PRCA) describes a condition in which RBC precursors in bone marrow are nearly absent, while megakaryocytes and WBC precursors are usually present at normal levels. Pure red cell aplasia exists in several forms, and the most common form is an acute self-limited condition. Congenital pure red cell aplasia is a lifelong disorder, and it is associated with physical abnormalities.

Approximately 90% of cases are sporadic, and one suggestion is that the sporadic cases are caused by in utero damage to erythroid stem cells.

In 10% of patients, a dominant, or more rarely recessive, familial pattern has been observed.

Clinical features

• Some, but not all, cases of congenital pure red cell aplasia are associated with severe anemias.
• More than one third of patients have malformations or mental retardation.
• In addition to anemia, approximately one third of patients develop physical abnormalities, most often involving the head, upper limbs, thumbs, urogenital system, or cardiovascular system.
• Growth retardation and unusual thumb formation can occur. However, these physical deformities are less severe than in Fanconi syndrome.
• Anemia is not often observed during the early neonatal period, but pallor, weakness, and dyspnea attributable to the anemia develop during the first year of life.
• Thymomas have not been found in these patients.

Tests and diagnosis

Basis studies

• CBC count
• Platelet count
• Differential count
• RBC indices
• Reticulocyte count
• Lactate dehydrogenase level
• Indirect bilirubin level
• Serum haptoglobin level

For congenital pure red cell aplasia, obtain the following:

• Fetal Hgb and erythrocyte adenine deaminase levels
• Serum folate and vitamin B-12 levels
• Genetic testing
• Peripheral smear results - Can show megaloblastic changes

Treatment

• Treatment is complicated because this condition is a lifelong disorder, and the consequences of treatment can have devastating effects on growth and sexual maturity.
• Transfusion is an integral modality in treating congenital pure red cell aplasia.
• Two units of blood every 2 weeks is usually sufficient.
• Aggressive chelation using deferrioxamine (ie, desferrioxamine) infusions are critical to avoid hemosiderosis because transfusion therapy is usually started at a young age.
• Corticosteroids are also a principal therapeutic option, and this therapy is believed to allow the abnormal stem cells in patients with congenital pure red cell aplasia to become more sensitive to growth factors. High doses of prednisone (ie, 1-2 mg/kg) are needed but should not be continued for more than 4-6 weeks. If prednisone therapy fails, a trial of high-dose methylprednisolone can be tried.
• Danazol and other androgens can be used in refractory cases, but these agents may be contraindicated in prepubertal children.

Prognosis

The mortality rate for acquired chronic pure red cell aplasia and for congenital pure red cell aplasia is expected to be slightly greater than that for the acute form of pure red cell aplasia