Congenital dyserythropoietic anaemia type II in a teenager presenting with severe anaemia.

Congenital dyserythropoietic anaemia (CDA) type II is a rare disease characterised by inefficient erythropoiesis and mononuclear cytopenia. Patients generally present with extravascular haemolytic anaemia, jaundice and splenomegaly. A female patient in her mid-teens presented with severe anaemia and abdominal distention. Medical history was significant for the diagnosis of β-thalassaemia intermedia made in her infancy. However, subsequent investigations showed normal reticulocyte counts that were disproportionate to the severity of her anaemia and a negative β-thalassemia mutation analysis, leading to concerns about a specific lineage disorder. A bone marrow trephine showed features typical of CDA type II-erythroid hyperplasia with multiple binucleate erythrocytes. CDA type II has often been mistaken for other congenital or acquired forms of anaemia; this case report intends to raise awareness among clinicians to consider CDA type II as a rare but possible cause of severe anaemia in a teenager with a previous presumptive diagnosis of β-thalassaemia .