Type 2: Idiopathic Sideroblastic Anemia (IASA)

Type 2: Idiopathic Sideroblastic Anemia (IASA)

• This is a more common form of S.A., occurring more frequently than Type One. It usually occurs during adulthood.
• The cause is not known, but has a predilection for patients >50 years old. It is often found when the patient visits the physician for some other supposed condition. This is a primary anemia and is also called “Refractory Anemia with Ringed Sideroblasts (RARS) because of the presence of ringed sideroblasts.
  
• It is considered to be a form of myelodysplastic syndrome.
• Two or more blood cell lines may be affected which may represent a refractory anemia with a form of a chronic-like leukemia. This occurs in a few patients and has a poor prognosis. Up to 10% of the patients with IASA may develop acute leukemia.
• The peripheral blood may present with a dimorphic RBC population in which anisocytosis, poikilocytosis, hypochromia, and basophilic stippling may be observed.
  
• One indicator of this variant is the bone marrow study that presents with >15% of the NRBC’s in the form ringed sideroblasts (and may make up 90%).
  
• A number of patients do not require medical intervention because the disease is non-progressive and benign. If the bone marrow of these patients presents with >30% ringed sideroblasts with abnormal granulopoiesis and megakaryocytopoiesis, the prognosis becomes poor.
  
• IRSA appears similar to erythroleukemia. To differentiate, the IASA rubriblast is periodic acid-Schiff negative whereas for erythroleukemia it is positive.
• Clinical laboratory findings are somewhat similar to other types of S.A.