Haematological disease in a child: Idiopathic thrombocytopaenic purpura (ITP)

Question 1

Define ITP.

Answer 1

Syndrome characterized by immune destruction of platelets resulting in bruising or a bleeding tendency.

Question 2

Explain the aetiology/risk factors for ITP.

Answer 2

Often idiopathic.

Acute ITP is usually seen weeks after a viral infection in children (chronic form more common in adults).
May be associated with infections (malaria, EBV, HIV), AI diseases (e.g. SLE, thyroid disease), malignancies and drugs (e.g. quinine). IgG autoantibodies produced by plasma cells in spleen that bind to platelet membrane proteins (glycoprotein IIb/IIIa + Ib/ IX) results in thrombocytopaenia. Antibody-bound complexes are then consumed by splenic macrophages, resulting in thrombocytopaenia.

Question 3

Summarise the epidemiology of ITP.

Answer 3

Acute ITP presents in children between 2 and 7 years. Chronic ITP is seen in adults, four times more common in women.

Question 4

What are the presenting symptoms of ITP?

Answer 4

Easy bruising

Mucosal bleeding

Menorrhagia

Epistaxis

Question 5

What are the signs of ITP?

Answer 5

Visible petechiae

Bruises (purpura or ecchymoses).

Typically, signs of other illness (e.g. infections, wasting, splenomegaly) would suggest other causes.

Question 6

What are appropriate investigations for ITP?

Answer 6

Diagnosis of exclusion: Exclude myelodysplasia, acute leukaemia, marrow infiltration.

Blood: FBC (reduced platelets), clotting screen (normal PT, APTT, fibrinogen), autoantibodies (antiplatelet antibody may be present but not used routinely for diagnosis, anticardiolipin antibody, antinuclear antibody).

Blood film: To rule out ‘pseudothrombocytopaenia’ caused by platelet clumping giving falsely low counts.

Bone marrow: To exclude other pathology. Normal or increased megakaryocytes.

Question 7

What is the management plan for ITP?

Answer 7

Oral corticosteroids.

Second-line therapy: IV infusion of immunoglobulin (IVIG). Platelet transfusions are usually contraindicated unless there is severe bleeding. In refractory cases, other immunosuppressants (e.g. azathioprine) may be used.

Surgery: Splenectomy has a 60 % cure rate in carefully selected patients.

Question 8

What are some complications associated with ITP?

Answer 8

Mucosal bleeding.

Major haemorrhage is rare (<1%).

Question 9

What is the prognosis of ITP?

Answer 9

Self-limiting in children, resolves in 1-2 months usually. Less likely to resolve in adults but can usually be controlled medically.