RESUMO
A 47 year-old patient with vitamin B12 deficiency and beta-thalassaemia trait is presented. A referring diagnosis of erythroleukaemia had been made. At admission the haemoglobin was 72 g/l; haematocrit,.221; mean corpuscular volume [MCV], 91.4 fl; white blood cell count, 2.6 x 109/l and platelet count, 68 x 109/l. Haemoglobin studies showed: haemoglobin A2 4.9% and haemoglobin F, 6.8% concentration. Bone marrow examination showed erythroid hyperplasia with severe dyserythropoiesis and increased immature cells resembling megaloblasts. Three months after treatment with vitamin B12 the pancytopenia resolved and the red blood cells showed microcytosis: haemoglobin, 158 g/l; haematocrit,.489, MCV, 67. 6fl; white blood cell count, 6.1 x 109/l; and platelet count, 384x 109/1. The levels of haemoglobin A2 and F remained elevated six months post-treatment. Two particular aspects are outlined: the absence of typical macrocytic anaemia when vitamin B12 deficiency is combined with thalassaemia trait and the need to rule out folate/vitamin B12 deficiency before establishing a diagnosis of haematopoietic malignancy with dyserythropoiesis such as erythroleukaemia