Myelodysplastic/myeloproliferative neoplasm with ring sideroblasts and thrombocytosis (MDS/MPN-RS-T) is a hybrid myeloproliferative and myelodysplastic neoplasm that contains thrombocytosis and ring sideroblasts.  There are also generally characteristic clinical and molecular abnormalities.

• Anemia with erythroid dysplasia (+/- multilineage dysplasia)
  • <1% blasts in the peripheral blood
  • <5% blasts in the bone marrow
  • ≥15% ring sideroblasts
• Platelet count >/= 450 K, which is persistent
• Does not meet the criteria for another hematopoietic neoplasm, specifically:
  • BCR–ABL1 negative
  • No PDGFRA, PDGFRB, FGFR1 rearrangements
  • PCM1–JAK2 negative
  • No t(3;3)(q21.3;q26.2), inv(3)(q21.3q26.2), or del(5q)
• No history of a myeloproliferative and/or myelodysplastic neoplasm.  There is an exception for a previous history of MDS with ring sideroblasts (MDS–RS).

• Anemia: Usually milder than that typically associated with myelodysplasia
• Splenomegaly is present in approximately 40% of cases

• Cytogenetic abnormalities – 10% of cases
• SF3B1 mutation – 60-90% of cases
  • >60% of cases have JAK2 mutation
  • <10% of cases have associated CALR or MPL mutations

Gurevich I, Luthra R, Konoplev SN, Yin CC, Medeiros LJ, Lin P. Refractory anemia with ring sideroblasts associated with marked thrombocytosis: a mixed group exhibiting a spectrum of morphologic findings. Am J Clin Pathol. 2011;135: 398–403. doi:10.1309/AJCPT0B6VEQPRCOA

 

Arber DA, Orazi A, Hasserjian R, Thiele J, Borowitz MJ, Le Beau MM, et al. The 2016 revision to the World Health Organization classification of myeloid neoplasms and acute leukemia. Blood. 2016;127: 2391–2405. doi:10.1182/blood-2016-03-643544

 

Swerdlow SH, Campo E, Harris, NL, Jaffe ES, Pileri SA, Stein H, Thiele J (Eds); WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues (Revised 4th edition). IARC: Lyon 2017