A smear macroscopically grainy: what is the likely cause?

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Multiple Choice

A smear macroscopically grainy: what is the likely cause?

Grainy appearance on a peripheral smear points to RBCs sticking together rather than dispersed cells. This clumping is classic for RBC agglutination caused by cold antibodies. In cold agglutinin disease, IgM antibodies attach to red cells at temperatures below normal body temperature and crosslink them, producing visible aggregates that give the smear a coarse, grainy look. If the sample is warmed to body temperature, the agglutination often reverses, supporting the diagnosis. Lipid droplets would make the plasma appear milky (lipemia) rather than cause grainy red cell clumps; plasma protein precipitation or platelet clumping produce different smear or plasma appearances, not the characteristic grainy RBC aggregates seen with cold agglutinins.

Grainy appearance on a peripheral smear points to RBCs sticking together rather than dispersed cells. This clumping is classic for RBC agglutination caused by cold antibodies. In cold agglutinin disease, IgM antibodies attach to red cells at temperatures below normal body temperature and crosslink them, producing visible aggregates that give the smear a coarse, grainy look. If the sample is warmed to body temperature, the agglutination often reverses, supporting the diagnosis. Lipid droplets would make the plasma appear milky (lipemia) rather than cause grainy red cell clumps; plasma protein precipitation or platelet clumping produce different smear or plasma appearances, not the characteristic grainy RBC aggregates seen with cold agglutinins.

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