Refractory Anemia with Ring Sideroblasts
Definition
- Myelodysplastic syndrome characterized by erythroid dysplasia with ring sideroblasts
Diagnostic Criteria
- Should be distinguished from RCUD because of longer median survival and lower rate of leukemic transformation
- Exclusions
- Non-clonal causes for dysplasia must be excluded (see Differential Diagnosis)
- If chemotherapy or radiation therapy related, should be reported as "therapy-related myeloid neoplasm"
- <1 x 103/μL monocytes (if present consider Chronic Myelomonocytic Leukemia)
- Lack of neutrophilia (if present consider BCR-ABL1+CML or atypical CML)
- Refractory anemia - Hemoglobin <10 mg/dL
- Ring sideroblasts (see definition below) ≥15% of total erythroid precursors (if <15% see RCUD)
- If >450x103/μL platelets in peripheral blood with marrow megakaryocytic proliferation, consider RARS-T
- This is a provisional mixed MDS/MPN entity that is commonly JAK2V617E mutated
- Peripheral blood blasts <1%, based on 200 leukocyte differential
- Bone marrow blasts <5%, based on 500 nucleated cell differential
- Cytogenetics should be performed on every patient to verify the presence of a clonal abnormality
- Present in about 10% of patients
- If no clone present, patient must be observed for 6 months before diagnosis of MDS is given
Morphologic features of erythroid dysplasia
- Dyserythropoeisis
- Dimorphic red blood cells (RBC)
- Mixture of normal or macrocytic RBC and hypochromic microcytic RBC
- High RDW
- Basophilic stippling (Pappenheimer bodies)
- Bone marrow erythroid lineage abnormalties
- Ring sideroblasts
- ≥5 iron granules encircling ≥1/3 of the nucleus
- Must involve ≥15% of erythroids to make the diagnosis of RARS
- Usually either many or none
- Erythroid hyperplasia
- Megaloblastoid / megaloblastic changes
- Dyssynchronous maturation of nucleus and cytoplasm of erythroid precursors
- Nucleus lags behind cytoplasm
- Dyssynchronous maturation of nucleus and cytoplasm of erythroid precursors
- Megaloblastoid / megaloblastic changes
- Cytoplasmic vacuoles
- Also seen in copper deficiency
- Nuclear changes
- Multinuclearity
- Nuclear budding, hyperlobulation and satellite nuclei
- Internuclear bridging
- Ring sideroblasts
- Often increased iron in histiocytes
- Due to lysis of defective erythrocytes
- Dimorphic red blood cells (RBC)
Dita Gratzinger MD PhD
Tracy I George MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342
Original posting:: 10/23/11