Acquired Aplastic Anaemia
Also known as: Acquired Aplastic Anemia
Acquired aplastic anaemia (Aaa) affects around 2 in 1,000,000 children each year. Affected children develop low blood counts due to the failure of production of normal blood cells by the bone marrow.
Medical text written July 1997 by Dr D Webb. Last updated September 2010 by Dr D Webb, Consultant Paediatric Haematologist/Oncologist, Great Ormond Street Hospital, London, UK.
Symptoms are due to the low number of normal blood cells. Reduced red blood cells (anaemia) causes pallor (a pale colour to the skin) and tiredness, reduced platelets (a condition known as thrombocytopaenia) results in bruising and, less often, bleeding because of a failure of blood to clot, and low white blood cells may result in fevers due to infections.
Almost all cases of aAA in children are due to the body’s immune system incorrectly attacking early bone marrow cells (stem cells). This attack may be triggered by a viral infection, including hepatitis. Most of the time, no cause is found.
Diagnosis requires taking two bone marrow samples called an ‘aspirate’ and a ‘trephine’, which allows doctors to measure whether the bone marrow is producing the correct amount of cells. Other tests are used to try and find the cause of the aAA, and to include those to identify other illnesses that may affect the bone marrow.
It is rare for the bone marrow to recover without treatment, which may either be by drugs that suppress the immune system, or by a stem cell transplant to replace those cells damaged in the bone marrow and to provide a new immune system which does not attack the bone marrow. Both treatments are very effective, but stem cell transplantation is often the treatment of first choice when a tissue matched donor is available. This is usually a brother or sister of the child with aAA. Identifying a donor requires blood samples to be taken from the immediate family. Over recent years it has become possible to find a stem cell donor who is unrelated to the patient, and this greatly increases the availability of donors. In some children with aAA, an unrelated stem cell transplant will be recommended when there is no family member who is suitable.
The immune suppressive drugs used when a stem cell transplant is not the chosen treatment are called antilymphocyte globulin (ALG) and ciclosporin. Both work by reducing the number and activity of immune system cells called T lymphocytes, which are responsible for attacking the bone marrow. A third drug, prednisolone, is given with the ALG to reduce allergic side effects of the ALG drug.