This uncommon disease tends to affect adults over the age of 50 years.
Infections such as the following can cause red cell aplasia
- HIV infection
- atypical pneumonia
- infectious mononucleosis
- mumps
- viral hepatitis
Some medications associated with development of red cell aplasia include:
- antiepileptic medications (eg, phenytoin, carbamazepine, sodium valproate)
- mycophenolate
- azathioprine
- chloramphenicol
- sulphonamides
- isoniazid
- clopidogre
Thymoma associated acquired primary red cell aplasia
- thymoma, a rare epithelial neoplasm, is the most common anterior-superior mediastinal tumour
- based on the appearance of neoplastic epithelial cells, the World Health Organization (WHO) has classified thymoma as type A (spindle or oval cells), type B (dendritic or epithelioid cells), and type C (exhibiting combined features of types A and B)
- thymoma can occur sporadically or in association with other conditions, such as myasthenia gravis, pure red cell aplasia (PRCA), and hypogammaglobulinemia (1)
- only 5% of thymoma cases develop PRCA. However, 10-50% of patients presenting with PRCA have an associated spindle cell type thymoma (2)
- PRCA is characterised by failure of erythropoiesis, with preserved granulopoiesis and megakaryopoiesis
- thymoma complicated by PRCA is associated with a poor outcome, and thymectomy provides a low PRCA remission rate in such patients
- hence, possible onset of PRCA should be anticipated, and close follow-up of these patients is recommended
Of patients with red cell aplasia:
- females predominate (2:1) in the thymoma group
- males dominate in the group without a thymoma
- 25-30% of patients undergo remission when the thymoma is removed. It is thought that the specific inhibition of red cell production is autoimmune-mediated - autoantigens include erythropoietin (1)
- exploratory thoracotomy is undertaken only when x-ray or CT scan show evidence of thymic enlargement.
Notes:
- most cases of acute transient primary red cell aplasia are caused by parvovirus B19 infection
- parvovirus 19 infections can persist longer in immunocompromised patients.
Reference:
- Handa SI, Schofield KP, Sivakumaran M, Short M, Pumphrey RSH. Pure red cell aplasia associated with malignant thymoma, myasthenia gravis, polyclonal large granular lymphocytosis and clonal thymic T cell expansion. J Clin Pathol. 1994;47:676-679.
- Lahiri TK, Agarwal D, Agarwal K, Shukla J. Pure red cell aplasia associated with Thymoma. Indian J Chest Dis Allied Sci. 2002;44(4):259-262.
- Sawada K, Fujishima N, Hirokawa M. Acquired pure red cell aplasia: updated review of treatment. Br J Haematol. Aug 2008;142(4):505-14
- Li G, Li ZQ, Yang QY, Yang JD. Acquired pure red cell aplasia due to treatment with clopidogrel: first case report. J Thromb Thrombolysis. Dec 3 2013
- Casadeval, N. et al.. Autoantibodies against erythropoietin in a patient with pure red cell aplasia. NEJM 1996;334(10): 630-3.
- Thompson DF, Gales MA. Drug-induced pure red cell aplasia. Pharmacotherapy. Nov-Dec 1996;16(6):1002-8.