What is Pure Red Cell Aplasia?
This is a form of anemia in which the bone marrow stops making red blood cells and this condition is known as Pure Red Cell Aplasia (PRCA). This results in anemia and reticulocytopenia, which is a condition where there is absence of young red cells.
What are the Types of Pure Red Cell Aplasia?
There are three types of PRCA:
Acquired Pure Red Cell Aplasia: This is an extremely rare type of Pure Red Cell Aplasia (PRCA) and it commonly affects adults. Patients with Acquired Pure Red Cell Aplasia will have absence of reticulocytes, which are red cell precursors, in the bone marrow. The red blood cell count is also low. However, the number of platelets and white blood cells are normal.
Congenital or Inherited Pure Red Cell Aplasia (Diamond-Blackfan Anemia): Inherited Pure Red Cell Aplasia is a genetic condition which often gets diagnosed during the first two years of life. Around 50% of patients will also suffer from mental retardation or physical malformations. The severity of Diamond-Blackfan Anemia varies from patient to patient.
Acute or Transient Self-Limited Pure Red Cell Aplasia (PRCA): This is the commonest type of Pure Red Cell Aplasia and is similar to acquired PRCA and differs only where at some point in time transient self-limited PRCA goes away on its own. A virus or drug triggers transient Pure Red Cell Aplasia (PRCA). Most of the times, after the offending drug is stopped or after the virus clears the transient Pure Red Cell Aplasia (PRCA) will disappear. Patients having a normal functioning bone marrow and who get affected with transient Pure Red Cell Aplasia (PRCA) can recover without even knowing that they had it. However, this condition is dangerous for patients suffering from chronic hemolytic anemia.
What are the Causes of Pure Red Cell Aplasia?
The cause of Pure Red Cell Aplasia (PRCA) is thought to be autoimmune in nature and this is a recent development. According to research, it is thought that patient's own immune cells mistakenly attack the blood-forming stem cells resulting in PRCA.
What are the Risk Factors for PRCA?
- Patients with autoimmune disorders, such as rheumatoid arthritis, are at increased risk for having Pure Red Cell Aplasia (PRCA).
- Certain viruses, such as the parvovirus B19, increases the risk of Pure Red Cell Aplasia (PRCA).
- Having an increased number of clonal large granular lymphocytes also increases the risk of Pure Red Cell Aplasia (PRCA).
- Tumors of the thymus or thymoma increase the risk of Pure Red Cell Aplasia (PRCA).
- Certain congenital genetic disorders which are seen in early childhood increase the risk of PRCA.
What are the Symptoms of Pure Red Cell Aplasia?
Patients suffering from Pure Red Cell Aplasia will have anemia; and symptoms of anemia include: Pale skin (pallor), fatigue, shortness of breath and dizziness. Acquired PRCA may be caused by an underlying condition which in turn will have other symptoms.
What is the Difference Between Aplastic Anemia & Pure Red Cell Aplasia?
The primary difference between aplastic anemia and Pure Red Cell Aplasia is that, in PRCA, only the red blood cells group is affected and the platelets and WBCs remain at normal levels; hence the name Pure Red Cell Aplasia. Whereas in aplastic anemia, all three types of blood cells are usually affected.
How is Pure Red Cell Aplasia Diagnosed?
Patient's medical history is taken and physical exam is done. The following blood tests are also done:
- A complete blood count (CBC) with a differential is done. This test looks at the type and the total number of blood cells in the patient's blood.
- A blood smear is done to microscopically examine the patient's blood.
- A reticulocyte count is done to determine the number of young red cells present in the patient.
- Bone marrow examination is done which consists of aspiration and biopsy to assess the bone marrow.
Who Should Be Consulted For Pure Red Cell Aplasia?
A hematologist with experience in bone marrow failure diseases should be consulted for treatment of Pure Red Cell Aplasia. If the cause of Pure Red Cell Aplasia is a rheumatoid disorder, then patient should also consult a rheumatologist.
How is Pure Red Cell Aplasia Treated?
The aim of treatment of Pure Red Cell Aplasia is restoring the production of red blood cells and treating any underlying disorder. The common treatments done for Pure Red Cell Aplasia are:
Blood Transfusions are done to increase the level of red blood cells. For patients who are not responding to other type of treatments will have to depend on blood transfusions on a continuous basis.
Corticosteroids are given to the patient as an initial treatment for PRCA. Corticosteroids often need to be given in large doses, which produce severe side effects in the patient. For this reason, corticosteroids are rarely used alone for treating PRCA.
Immunosuppressive therapy is done if the underlying cause of the PRCA is immunological and if the patient is not responding to corticosteroids. Other medications for PRCA comprise of azathioprine, cyclosporine, cyclophosphamide with or without corticosteroids, and anti-thymocyte globulin. Rituximab may be effective in some patients. If virus is the cause of PRCA (especially B19 parvovirus) then immunoglobulin infusions are given for treatment. Surgery is needed for treating thymoma-associated PCRA where the thymoma is removed surgically. After immunosuppressive therapy there is significant relapse rate, however, treatments can be repeated.