Pure red cell aplasia (PRCA) is characterized by profoundly decreased or absent erythroid precursors in the bone marrow, leading to severe anemia and low reticulocyte count, while WBC count and platelet count remain normal.

PRCA may be acquired or inherited. Causes of acquired PRCA include drug effect, infection, autoimmune conditions, and malignancy and its management. Acquired PRCA mainly occurs in older adults. The best understood mechanisms of acquired PRCA are cases that result from T-cell mediated autoimmune destruction of red cells (T-cell suppression and destruction of red cells in the setting of malignancy, thymoma, or other disorders) and those that result from parvovirus B19 infection (which preferentially infects erythroid progenitor cells and, if persistent, causes PRCA). Other viral infections can cause transient red cell aplasia but are often unrecognized. Some acquired cases are drug-induced. Medications implicated include antiepileptic medications, sulfonamides, mycophenolate, azathioprine, chloramphenicol, thiamphenicol, isoniazid, procainamide, and clopidogrel. A generally self-limited form of red cell aplasia is seen in the first year of life and is known as transient erythroblastopenia of childhood.

Inherited PRCA is known as Diamond-Blackfan anemia, which presents at birth or within the first year of life. It is a very rare condition and is associated with mutations in RPS19 and RPS.