6. Sideroblastic Anemia
Sideroblastic anemias (SAs) are characterized by ringed sideroblasts (erythroblasts containing iron-positive granules arranged around the nucleus) in the bone marrow. Sideroblastic anemias, which can be inherited or acquired, exhibit impaired heme biosynthesis in erythroid progenitors. Most sideroblastic anemias are acquired as clonal disorders of erythropoiesis. Additionally, ringed sideroblasts can be found in malnourished patients who abuse alcohol [17].
Drug-induced sideroblastic anemia has been associated with isoniazid [18]. The anemia is reversed by pyroxidine or by withdrawal of isoniazid. Chloramphenicol, rarely used at present, causes a reversible suppression of erythropoiesis and produces ringed sideroblasts [17]. Linezolide, penicillamine, and triethylene tetramine dihydrochloride (a chelating agent used to treat Wilson's disease) induce reversible SA [19–21]. Myelodysplasias and secondary acute leukemias induced by chemotherapy, discussed below, may initially manifest as sideroblastic anemia [22].