CDA is a rare, inherited dyserythropoeitic anaemia characterised by ineffective erythropoiesis and intramedullary haemolysis. The inheritance is autosomal recessive. The fraction of haemoglobin F is often increased. CDA is classified into the following types based on bone marrow morphology:
- Type 1: occasional (3-7%) binucleate erythroblasts, inter-nuclear bridging
- Type 2: multi-nucleated late erythroblasts
- Type 3: gigatoblasts (erythroblasts with >=8 nuclei)
Complications
- Iron overload
- Gallstones and cholecystitis / cholangitis
- Hypersplenism – may necessitate splenectomy, may particularly benefit type 2 patients
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Blood film features:
- Anisopoikilocytosis, often marked
- May have dimorphic picture
- Some macrocytes, most cells normocytic
- Teardrop cells
- Basophilic stippling
- nRBCs may be seen, especially after splenectomy (look for features of splenectomy)
- Other cell lines lack dyserythropoietic features
Differential diagnosis:
- Haemoglobin H disease (microcytic, hypochromic with polychromasia)
- Hereditary pyropoikilocytosis (microspherocytes, elliptocytes, red cells with bud-like projections and polychromasia)
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Bone marrow features:
- Hypercellular marrow
- Erythroid hyperplasia with sometimes reversed myeloid:erythroid ratio
- Type 1 will have inter-nuclear bridging
- Type 2 and type 3 will have multinucleated erythroblasts
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