Diagnosis and treatment of pure red cell aplasia.

Pure red cell aplasia is a selective aplasia of the marrow erythroid cells. Unlike aplastic anemia, the marrow has a normal cellularity and the patients generally have normal leukocyte and platelet blood counts. The congenital form of the disease occurs in the firlst 1 1/2 years of life and is often responsive to corticosteroids. The acquired form may be secondary to infections, drugs, chemicals, or hemolytic anemia (aplastic crisis). In these cases it is often acute and self-limited with cessation of the infection or drug ingestion. It may also be secondary to systemic lupus erythematosus, rheumatoid arthritis, acute severe renal failure, severe nutritional deficiency, or diverse neoplasms, and may remit with treatment of the primary condition. When a thymoma is present, it should be resected since a remission is produced in 29 per cent of these patients. The remaining patients have an acquired primary form of the disease that tends to be chronic and in some cases may have an immune pathogenesis. A cytotoxic immunoglobulin inhibitor of the marrow erythroid cells or erythropoietin has been described and these patients may respond to prednisone and/or to cytotoxic immunosuppressive drugs such as cyclophosphamide and 6-mercaptopurine. Pure red cell aplasia appears to be more common than the literature has revealed and has stimulated much investigation into an immune pathogenesis for marrow failure.