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Cold Agglutinin Disease — RACP Adult Medicine MCQ

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ModerateHaematologyCold Agglutinin DiseaseRACP Adult Medicine

A 72-year-old man presents with acrocyanosis, Raynaud phenomenon, and anaemia. DAT is positive for C3d only. Cold agglutinin titre is 1:512 at 4°C. Blood film shows red cell agglutination. He has underlying CLL. What is the most likely diagnosis?

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Correct answer: D — Cold agglutinin disease

DAT positive for C3d only (not IgG) with high cold agglutinin titre and red cell agglutination is diagnostic of cold agglutinin disease. It is often secondary to lymphoproliferative disorders (CLL, lymphoma) or Mycoplasma infection. Treatment is cold avoidance; rituximab-based therapy for severe/symptomatic cases. Steroids are less effective than in warm AIHA.

Reference: BSH – 2024 – AIHA Guidelines