Ringed Sideroblasts are seen in-

In MDS ( myelodysplastic syndrome),within the erythroid series , common abnormalities include ring sideroblasts ,erythroblasts with iron laden mitochondria visible as perinuclear granules surrounding 1/3 rd of the nucleus in prussian blue stained aspirates or biopsies. Ref: Robbins and Cotrans Pathologic basis of disease;pg :615 under morphology.