 This explains him also having anemia, caused by chronic Acquired Pure Red Cell Aplasia (PRCA), probably resulting from blood doping.After responding to prednisone, Jeff begins losing more red blood cells, to the point of requiring a transfusion.House scans Jeff's neck and a thymoma is discovered; an extremely rare tumor on the thymus, confirming that he wasn't taking EPO, but did have Chronic Acquired Pure Red Cell Aplasia.