An 80-year-old woman with a 2-year history of myelodysplastic syndrome/myeloproliferative neoplasm with ring sideroblasts and thrombocytosis, SF3B1 positive, was referred to our clinic for a second opinion regarding worsening transfusion dependency of red blood cells (every 1-2 weeks for a maximal hemoglobin count of 60 g/L). Due to the multiple transfusions, the patient exhibited iron overload, with a ferritin level of 694 μg/L despite iron chelation (deferasirox). The patient underwent a bone marrow examination before initiation of luspatercept. Iron staining (Prussian blue) of the bone marrow showed, in addition to the usual signs of iron overload, a probable endothelial deposition of the iron in the vessels (see arrows in panels A-C; panel A, 10× magnification; panel B, 50× magnification; panel C, 100× magnification).

It has been hypothesized that circulating iron may aggravate arteriosclerosis through endothelial deposition, oxidative stress, and macrophage activation leading to endothelial dysfunction, and is thus a precipitating factor for advanced cardiovascular disease. An optimal iron chelation therapy could improve endothelial function and lessen the risk of cardiovascular disease in these patients. It is very rare to see a capillary vessel in the bone marrow cytology, and thus this examination is not ideal for follow-up of these iron deposits in the vessels.