sidéroblaste en couronne

CONT: Quand [un] excès de fer se localise aux mitochondries, témoin d’une perturbation de la synthèse d’hémoglobine, et que ces mitochondries viennent se localiser autour du noyau, visibles à la coloration de Perls sous la forme de granulations colorées par le bleu de Prusse et disposées sur au moins un tiers du pourtour nucléaire, on définit le sidéroblaste en couronne, caractéristique nécessaire à la définition d’une anémie sidéroblastique.

CONT: Ring sideroblasts are erythroblasts with iron-loaded mitochondria visualized by Prussian blue staining (Perls’ reaction) as a perinuclear ring of blue granules. ... The International Working Group on Morphology of Myelodysplastic Syndrome (IWGM-MDS) recommended that ring sideroblasts be defined as erythroblasts in which there are a minimum of five siderotic granules covering at least one third of the circumference of the nucleus. Ring sideroblasts are found exclusively in pathological conditions, and should not be confused with ferritin sideroblasts, which are present in normal bone marrow. ... While the iron of ferritin sideroblasts is stored in cytosolic ferritin, whose subunits are encoded by the FTH1 and FTL genes, the iron of ring sideroblasts is stored in mitochondrial ferritin, encoded by the FTMT gene.