Refractory anemia with ring sideroblasts and RARS with thrombocytosis

Area of Science:

• Hematology
• Oncology
• Genetics

Background:

• Ring sideroblasts (RS) define specific myeloid neoplasms: refractory anemia with ring sideroblasts (RARS) and RARS with thrombocytosis (RARS-T).
• RARS is a lower-risk myelodysplastic syndrome (MDS) with erythroid dysplasia and ≥15% bone marrow (BM) RS.
• RARS-T is a provisional MDS/MPN overlap syndrome with RARS features plus thrombocytosis and atypical megakaryocytes.

Purpose of the Study:

• To outline the diagnostic criteria for RARS and RARS-T.
• To discuss the genetic mutations associated with these conditions.
• To review risk stratification and management strategies.

Main Methods:

• Diagnosis relies on bone marrow morphology, blast counts, RS percentage, and platelet counts.
• Genetic analysis identifies key mutations, notably SF3B1 in RARS/RARS-T and JAK2V617F in RARS-T.
• Prognostic scoring systems (IPSS) and clinical features guide risk stratification.

Main Results:

• SF3B1 mutations are present in ≥80% of RARS and RARS-T patients, correlating with RS.
• RARS-T patients frequently have JAK2V617F mutations (∼60%).
• RARS-T shows a better outcome than RARS but worse than essential thrombocytosis, with a low risk of leukemic transformation for both.

Conclusions:

• RARS and RARS-T are distinct myeloid neoplasms with specific diagnostic and genetic profiles.
• Management involves addressing anemia and iron overload, with cautious use of aspirin and further study of lenalidomide for RARS-T.
• Both conditions have a low risk of transformation to acute leukemia.