Aplastic Anaemia

Question 1

Define aplastic anaemia

Answer 1

Anaemia with diminished haematopoietic precursors in the bone marrow and pancytopaenia

Question 2

What are the causes/risk factors of aplastic anaemia?

Answer 2

Acquired:
• Idiopathic (>40%): May be due to destruction or suppression of the stem cell by autoimmune mechanisms.
• Drugs: Chloramphenicol, Sulphonamides, Gold, Alkylating agents, Anti-epileptics, Methotrexate, Nifedipine
• Chemicals DDT, Benzene
• Radiation
• Viral infection: B19 parvovirus, HIV, EBV.

Inherited:
• Fanconi’s anaemia: Autosomal Recessive and X-linked; caused by an error of DNA repair. Characterized by familial aplastic anaemia, short stature, abnormality of thumbs, café au lait spots, microcephaly, hypogonadism and renal tract defects.
• Dyskeratosis Congenita: X-linked; Aplastic anaemia associated with classical triad: abnormal nails, mucosal leukoplakia and reticulated skin rash.

Question 3

What are the signs and symptoms of aplastic anaemia?

Answer 3

• Anaemia - tiredness, fatigue, SoB; Pallor.
• Leucopoenia - increased frequency and severity of infections with no hepatosplenomegaly or lymphadenopathy.
• Thrombocytopaenia - bleeding, epistaxis and easy bruising; Petechiae and bruises.

Question 4

What investigations are carried out for aplastic anaemia?

Answer 4

• FBC - normocytic Anaemia, Thrombocytopaenia, Leucopaenia.
- Low Reticulocyte Count.
• Blood Film - to exclude Leukaemia –abnormal circulating blood cells.
• Bone Marrow Biopsy - to identify the cause and exclude other disorders e.g. myelodysplasia.
- A hypocellular marrow is a definitive diagnostic finding for AA. Moreover, there should be an absence of abnormal cell population (such as blasts) and no fibrosis.
• Genetic Tests -
Diepoxybutane Test (DEB) for Fanconi’s Anaemia. Presence of increased chromosomal breakage in lymphocytes cultured in the presence of DNA cross-linking agents e.g. mitomycin C.