FRCPath Haematology Part 2: Morphology RBC Morphology Overview Dimorphic Picture

Dimorphism – presence of two distinct populations on blood film

Causes:

  • Transfusion
  • Siderblastic anaemia
  • Deficiency of both iron and B12/folate
  • Delayed transfusion reactions
Dimorphic Picture. Peripheral blood film from a patient with haemoglobin E / ß thalassaemia compound heterozygosity, showing the native hypochromic, microcytic population with numerous target cells, and a transfused population with normochromic, normocytic red blood cells. The dimorphic appearance is often more apparent at lower magnification.
Peripheral blood film from a patient with haemoglobin E / ß thalassaemia compound heterozygosity, showing the native hypochromic, microcytic population with numerous target cells, and a transfused population with normochromic, normocytic red blood cells. The dimorphic appearance is often more apparent at lower magnification.
Dimorphic Picture. Peripheral blood film from a patient with haemoglobin E / ß thalassaemia compound heterozygosity, showing the native hypochromic, microcytic cells (red arrow), and transfused normochromic, normocytic red cells (green arrow).
Higher magnification. Peripheral blood film from a patient with haemoglobin E / ß thalassaemia compound heterozygosity, showing the native hypochromic, microcytic cells (red arrow), and transfused normochromic, normocytic red cells (green arrow).
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