Une anémie de Biermer se dissimulant sous les traits d’une anémie normocytaire

Dewulf, Joseph P. [UCL] Dermine, Alexandre [UCL] Defour, Jean-Philippe [UCL] Vekemans, Marie-Christiane [UCL]

L’anémie mégaloblastique par carence en vitamine B12 ou en folate est bien connue. Son diagnostic est aisément posé par l’association d’une carence en vitamine et d’une macrocytose globulaire. Toutefois, diverses circonstances peuvent masquer la macrocytose et, donc, compliquer le diagnostic. Nous rapportons le cas d’une patiente se présentant pour une anémie hémolytique normocytaire qui s’avère être après mise au point, une anémie de Biermer associée à une alpha-thalassémie mineure.

(eng) [A pernicious anemia masking itself under the guise of a normocytic anemia] Megaloblastic anemia due to vitamin B12 or folate deficiency is a well-known clinical entity. Diagnosis is easily made on the basis of vitamin deficiency associated with macrocytosis. Several conditions can, however, hide the conventional macrocytosis, rendering the diagnosis less straightforward. We report the case of a 45-year-old woman presenting with relatively well-tolerated severe anemia (7g/dL) and mild thrombocytopenia. The mean corpuscular volume (MCV) was normal (86,9 fL) with low reticulocytosis. Biology revealed signs of hemolysis and a low vitamin B12 level combined with anti-intrinsinc factor antibodies, which corroborated the diagnosis of pernicious anemia. To exclude a bicytopenia of central origine, a bone marrow aspiration was performed, which confirmed the megloblastosis. the normal MCV prompted us to search for a cause that could mask the classic macrocytosis observed in megaloblastic anemias. Ferritin and C-reactive protein levels were in the normal range, as was hemoglobin electrophoresis. We finally detected an α+thalassemia with 3,7 kb deletion while using molecular biology techniques. The patient recovered within a few weeks after being given intramuscular vitamin B12. This case of normocytic hemolytic anemia that turned out to be a pernicious anemia associated with an alpha-thalassemia minor illustrates that normal MCV does not suffice to rule out vitamin B12 deficiency. The major reasons for normocytic anemia under these circumstances are its combination with microcytic anemia, mostly due to iron deficiency and thalassemia, or its coexistence with macrocytic erythrocytes comprising erythrocyte fragments