Acquired Pure Red Cell Aplasia is a rare bone marrow disorder characterized by an isolated decline of red blood cells (erythrocytes) produced by the bone marrow. Affected individuals may experience fatigue, lethargy, and/or abnormal paleness of the skin (pallor). Acquired Pure Red Cell Aplasia may occur for unknown reasons (idiopathic) or as a primary autoimmune disorder. It is also believed that Acquired Pure Red Cell Aplasia may occur secondary to a tumor of the thymus gland (thyoma), viral infections, or certain drugs.

Acquired Pure Red Cell Aplasia is thought to be an autoimmune disorder possibly caused either by a tumor of the thymus gland, certain drugs or a viral infection. It is one of a group of bone marrow failure syndromes.