A 71-year-old woman without any hematological history was investigated for chronic, progressive normocytic anemia. Her hemoglobin was 69 g/L with a mean corpuscular volume of 89.3 fL, white cell counts were normal. White blood cell differentiation showed 2.5% immature granulocytes and a basophilia of 0.9 x10^9/L. Platelet count was high (666 × 10^9/L). Blood film showed marked red cell anisocytosis, poikilocytosis with with presence of acanthocytes, tear drop cells, fragmentocytes and eliptocytes. There was nuclear hypersegmentation and cytoplasmatic hypogranulation. No blast were observed.

Bone marrow aspirate smear demonstrated marked hypercellularity, increased erythroid precursors with features of mild dyserythropoiesis such as karyorhexxis, multinuclear forms. There was an increase in large mono- and hypolobated megakaryocytes, rare presence of micromegakaryocyte and megakaryoblast. Futhermore there was a marked dysplasia of neutrophils comparable to dysplasia seen in peripheral blood and the blast count was 7%. Iron-stained marrow smear revealed numerous ring sideroblasts comprising >50% of erythroid precursors. The diagnosis was myelodysplastic/myeloproliferative neoplasm with ring sideroblasts and thrombocytosis (MDS/MPN-RS-T), which is an entity of myelodysplastic/myeloproliferative neoplasm according to World Health Organization classification. Bone marrow cytogenetics showed a normal karyotype and molecular test results for JAK2-V617F and CALR mutations were negative. Molecular analysis showed the presence of presumable pathogenic variants in the ASXL1_exon 12 which are recurrent in several myeloïd neoplasms and are associated with a negative prognosis.
The SF3B1 mutation, which is found in 60-90% of the MDS/MPN-RS-T cases, was not detected.