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Immune thrombocytopenia mechanism — MRCPCH TAS MCQ

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ModerateImmunologyImmune thrombocytopenia mechanismMRCPCH TAS

A 4-year-old develops petechiae two weeks after a viral illness. Platelets are 8 x 10^9/L; haemoglobin and white cells are normal. What is the most likely immune mechanism?

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Correct answer: C — IgG-mediated platelet destruction

Immune thrombocytopenia is commonly due to IgG autoantibodies against platelet antigens, causing splenic destruction. IgA deposition in small vessels describes IgA vasculitis, which would have palpable purpura and often abdominal pain. The pearl is that isolated thrombocytopenia with a well child supports ITP over marrow failure.

Reference: Nelson Textbook of Pediatrics; RCPCH Theory examination syllabi; Lissauer's Illustrated Textbook of Paediatrics