Thursday, August 29, 2013

APLASTIC ANAEMIA

An 18 year old adult presents to your office with complaints of fever, fatigue and lethargy for 1 week duration. He also gives you a history of fever, sore throat and numerous swellings around his neck 3 weeks back and it resolved spontaneously. He has no other complaints. On examination, his vitals are:     P- 100bpm, BP- 110/80 mmHg, temp.- 1000F, RR- 20/min. On general examination, you observe purpuric and ecchymotic rashes on the anterior of shin, thigh and trunk. His liver and spleen are not palpable. How will you proceed with the management of this case?

  • Pancytopenia with hypocellularity (aplasia) of the bone marrow; there are no leukaemic, cancerous or other abnormal cells in the peripheral blood or bone marrow. 
  •  inherited and acquired.
  • Reduction in the number of pluripotential stem cells
  • Failure of only one cell line e.g. RBCs results  in pure red cell aplasia. 
  •  Myelodysplasia, paroxysmal nocturnal haemoglobinuria (PNH) or acute myeloblastic leukaemia occurs in some cases due to an abnormal clone of haemopoietic cells.
  • Activated cytotoxic T cells in blood and bone marrow are responsible for the bone marrow failure.
Causes of aplastic anaemia

Primary
  • Congenital, e.g. Fanconi's anaemia 
  • Idiopathic acquired (67% of cases) 
Secondary
  • Chemicals, e.g. benzene 
  • Drugs: 
  • chemotherapeutic 
  • idiosyncratic reactions 
  • Insecticides
  • Ionizing radiation 
  • Infections: 
  • viral, e.g. hepatitis, EBV, HIV, parvovirus 
  • other, e.g. tuberculosis 
  • Paroxysmal nocturnal haemoglobinuria 
  • Miscellaneous, e.g. pregnancy 
  • Busulfan ,doxorubicin, chloramphenicol, gold, carbimazole, chlorpromazine, phenytoin, tolbutamide, non-steroidal anti-inflammatory agents, 
  •  Gene mutations e.g. the telomerase RNA component, in one third of aplastic anaemias. 
  • Fanconi's anaemia ,inherited as an autosomal recessive, is associated with skeletal, renal and central nervous system abnormalities, ages of 5 and 10 years. 
Clinical features
  • Anaemia, bleeding and infection(oral). 
  • Bruising with minimal trauma or blood blisters in the mouth. 
  • Physical findings include ecchymoses, bleeding gums and epistaxis. 
  • Lymphadenopathy and hepatosplenomegaly are rare.
Investigations
  • Peripheral smear
  • pancytopenia 
  • the virtual absence of reticulocytes 
  • a hypocellular or aplastic bone marrow with increased fat spaces
Causes of pancytopenia
  • Aplastic anaemia
  • Drugs 
  • Megaloblastic anaemia 
  • Bone marrow infiltration or replacement   
  • Hodgkin's and non-Hodgkin's lymphoma
  • Acute leukaemia   
  • Myeloma
  • Myelofibrosis 
  • Hypersplenism 
  • Systemic lupus erythematosus
  • Disseminated tuberculosis 
  • Paroxysmal nocturnal haemoglobinuria 
  • Overwhelming sepsis
Treatment and prognosis

Supportive care, specific treatment
Treatment of infection – if any.
Immediate institution of broad-spectrum parenteral antibiotics in neutropenic patient – prophylactic in all cases.
Supportive care: transfusions of red cells and platelets

A bad prognosis (i.e. severe aplastic anaemia) if two of the following three features:
neutrophil count of less than 0.5 × 109/L
platelet count of less than 20 × 109/L
corrected reticulocyte count less than 1% (or absolute reticulocyte count less than 60,000/L).
Survival of patients  is about 20% at 1 year after diagnosis with  supportive care;

Suspect exposures to drugs or chemicals should be discontinued;

HEMATOPOIETIC STEM CELL TRANSPLANTATION

Treatment of choice for patients under 40 years of age who have an HLA-identical sibling donor, which gives a 75-90% chance of long-term survival, restores the blood count to normal.
Immunosuppressive therapy  for patients without HLA-matched siblings and over the age of 40 years; antilymphocyte globulin (ALG) and ciclosporin in combination(60-80%).

Androgens (e.g. oxymethalone)
Steroids   are  used in children with congenital pure red cell aplasia (Diamond-Blackfan syndrome).
Adult pure red cell aplasia is associated with a thymoma in 30% of cases and thymectomy may induce a remission.

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