Introduction.
Rare, indolent, and likely due to stepwise accumulation of molecular mutations, MDS/MPN overlap syndrome with ring sideroblasts and thrombocytosis (MDS/MPN-RS-T) is a myeloid neoplasm associated with dysplasia and cytopenias as well as myeloproliferation and cytoses1. Therefore, in this entity, driver mutations of JAK2 V617F but also CALR and MPL W515 have been attributed to the proliferative features whereas the presence of ring sideroblasts, dyserythropoiesis and cytopenias are chiefly associated with SF3B1 (K700E) or other similar mutations2. Previously being a provisional entity in the 2008 iteration of WHO, this disorder is now fully characterized requiring persistent thrombocytosis (> 450 x 109/L), anemia with erythroid /multilineage dysplasia, ≥15% ring sideroblasts, <1% blasts in the peripheral blood and <5% blasts in the bone marrow. Other diagnostic requirements include the presence of SF3B1 mutation and lack of reactive causes of ring sideroblasts, diagnosis of other myeloproliferative or myelodysplastic entities and absence of certain gene rearrangements diagnostic of other myeloid neoplasms (i.e. BCR-ABl1, PDGFRA , PDGFRB ,FGFR1 ,PCM1-JAK2, t(3;3) (q21q26), inv (3)(q21q26) or del (5q) (MDS with thrombocytosis) )1 . Here we describe a case of an elderly patient with hematomas, and critical thrombocytosis (initially suspect for acquired von Willebrand disease) who was diagnosed with MDS/MPN-RS-T.