Rare Disease Spotlight - Aplastic Anemia

Bill Loguidice

Aplastic anemia (AA) is a syndrome of bone marrow failure in which the production of new blood cells ceases or slows down, leading to a deficiency of all three blood cell types (ie, pancytopenia). Subsequently, patients develop anemia (most often normocytic), leukopenia, and thrombocytopenia. AA can develop at any age, may occur suddenly or slowly, and can progress to become severe enough to be fatal. In the United States, between 600 and 900 people receive an AA diagnosis each year.1 Although AA can affect anyone, it is most common among children, teenagers, older adults, and persons of Asian descent.1

Many factors can cause AA, including radiation and chemotherapy treatments, exposure to toxic chemicals, use of certain drugs, autoimmune disorders, viral infections, and pregnancy. Sometimes the disease is idiopathic.

Patients with AA often feel fatigued and have a higher risk of infections and uncontrolled bleeding than the general population. Other common symptoms include shortness of breath during exertion, a rapid or irregular heart rate, pallor, unexplained or easy bruising, skin rash, dizziness, and headaches. To diagnose AA, blood tests are taken to determine if all three blood cell levels are low. This is commonly followed by a bone marrow biopsy to assess if the bone marrow contains fewer blood cells than normal. Finding a hypoplastic bone marrow with fatty replacement and, potentially, an increase in nonhematopoietic elements, such as mast cells, is often diagnostic for AA; however, other conditions need to be carefully considered and ruled out, as AA remains a diagnosis of exclusion (Table).2,3 When a definitive diagnosis is made, if the etiology remains unclear, additional tests may be undertaken to determine an underlying cause.

Table. Differential Diagnosis for Aplastic Anemia

  Acute Lymphoblastic Leukemia
 Acute Myelogenous Leukemia
 Agnogenic Myeloid Metaplasia With Myelofibrosis
 Human Herpesvirus Type 6
 Megaloblastic Anemia
 Multiple Myeloma
 Myelodysplastic Syndrome
 Myelophthisic Anemia
 Non-Hodgkin Lymphoma
 Paroxysmal Nocturnal Hemoglobinuria

Mild cases of AA may only require observation. AA caused by most drugs, as well as radiation and chemotherapy treatments for cancer, usually improve once treatment courses are completed. Pregnancy-induced AA may also improve once pregnancy ends; however, relapse has been reported in 33% of patients.4 More serious cases may require blood transfusions and medications, including immunosuppressive agents, and may be escalated to include stem cell and bone marrow transplantation.

With timely standard treatments, between 70% and 90% of patients with AA improve.5 However, the chance for recovery depends on many factors, including disease severity, response to treatment, and patient age. Higher survival rates have been reported for younger patients, with the overall 5-year survival rate at about 80% for patients younger than age 20 years who have received a stem cell or bone marrow transplant to treat their AA.6 In cases of severe and very severe aplastic anemia, prompt treatment is essential, as a mortality rate of greater than 70% has been reported with supportive care alone.7


1. Aplastic Anemia & MDS International Foundation. Frequently Asked Questions: How many people are diagnosed with aplastic anemia each year? Accessed May 17, 2015.
2. Bakhshi S. Aplastic anemia workup. Updated September 10, 2014. Accessed May 17, 2015.
3. Guinan EC. Diagnosis and management of aplastic anemia. Published 2011. Accessed May 17, 2015.
4. Marsh JC, Ball SE, Cavenagh J, et al; British Committee for Standards in Haematology. Guidelines for the diagnosis and management of aplastic anaemia. Br J Haematol. 2009;147(1):43-70.  
5. Aplastic Anemia & MDS International Foundation. Frequently Asked Questions: How long do I have to live? Accessed May 17, 2015.
6. St. Jude Children’s Research Hospital. Disease Information: What are the survival rates for aplastic anemia? Accessed May 17, 2015.
7. Camitta BM, Thomas ED, Nathan DG, et al. A prospective study of androgens and bone marrow transplantation for treatment of severe aplastic anemia. Blood. 1979;53(3):504-514.

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