Define Immune Thrombocytopenic Purpura. Describe its clinical features, investigations, diagnosis and management.

Definition

• Immune (idiopathic) thrombocytopenic purpura (ITP) is an acquired disorder of immune-mediated platelet destruction (antibody-coated platelets removed by the spleen), causing isolated thrombocytopenia.
• It is the commonest cause of acute thrombocytopenia in a well child.

Clinical Features

• Often follows a viral infection 1–3 weeks earlier; typically a well child aged 2–6 years.
• Sudden petechiae, purpura and bruising; mucosal bleeding (epistaxis, gum bleeding).
• No hepatosplenomegaly or lymphadenopathy (their presence suggests another diagnosis, e.g. Leukaemia).

Investigations

• Isolated thrombocytopenia with a normal haemoglobin and white-cell count; large (young) platelets on the smear.
• Bone marrow (if atypical) shows normal or increased megakaryocytes.
• It is largely a diagnosis of exclusion.

Management

• Acute childhood ITP is usually self-limiting — most recover within weeks to months.
• Observation for mild disease (skin signs only); avoid trauma, contact sports and antiplatelet drugs.
• For significant bleeding or very low counts — corticosteroids, IV immunoglobulin, or anti-D.
• Chronic ITP (> 12 months) — further options (thrombopoietin agonists, rituximab, splenectomy).

Differential Diagnosis

• Leukaemia (look for anaemia, neutropenia, blasts, organomegaly), aplastic anaemia.
• Other causes of thrombocytopenia — infections (dengue), drugs, hypersplenism, SLE.

Complications & Prognosis

• Serious bleeding (including rare intracranial haemorrhage) is the main risk with very low counts.
• Most childhood ITP resolves spontaneously within 6–12 months with an excellent prognosis; a minority become chronic.

When to Investigate Further / Suspect Another Cause

• Abnormal haemoglobin or white cells, organomegaly or lymphadenopathy → bone marrow to exclude leukaemia/aplasia.
• Atypical age, chronic course, or failure to respond to standard therapy.