The Pathology of Pure Red Cell Aplasia

By: Neal Shah, Co Editor-In-Chief

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Pure Red Cell Aplasia (PRCA), also known as erythroblastopenia, is characterized by a suppression of erythrocytes in the bone marrow.  It is a peculiar oddity that the bone marrow’s progenitor cells still differentiate into white blood cells and platelets.¹  PRCA has idiopathic, viral, auto-immune, and genetic etiologies.  Diamond-Blackfan syndrome features PRCA due to defective red blood cell (RBC) production¹ resulting from genetic abnormalities in ribosomal protein production.²  Infection with the parvovirus B19 is linked to PRCA in immunocompromised patients,³ and thymomas often present in up to 15% of PRCA cases.⁴

Drug induced PRCA is often seen with administration of erythropoiesis stimulating agents (ESA) such as Aranasp® (darbepoeitin) and Procrit® (epoeitin).⁵  The administration of these exogenous peptides results in antibody formation and subsequent destruction of erythrocyte precursors.  PRCA occurs most frequently when ESAs are administered subcutaneously.⁶  Discontinuation of the ESA usually does not stop PRCA from occurring, but immunosuppressive agents are shown to slow progression.⁷  In March 2012, the FDA approved the drug Omontys® (peginesatide).⁸  This drug does not resemble typical ESA because it is not a direct erythropoietin mimetic; instead it is a pegylated dimer that directly activates erythropoesis.  It is currently indicated for the treatment of anemia due to chronic kidney disease for patients on dialysis.¹⁰

Treatment of PRCA involves discontinuation of all ESA agents and a course of corticosteroids to suppress the immune system.¹¹  Some immunosuppresants including cyclophosphamide and cyclosporine are also successful in mitigating PRCA.^12,13  Rituximab is also shown to be effective in treating PRCA.¹⁴

SOURCES:

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12. Gupta R, Ezeonyeji A, Thomas A, Scully M, Ehrenstein M, Isenberg D. A case of pure red cell aplasia and immune thrombocytopenia complicating systemic lupus erythematosus: Responseto rituximab and cyclophosphamide. Lupus. 2011;20(14):1547—1550.
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