CD34 and acquired polycythemia vera: Ph-negative myeloproliferative neoplasms (MPNs, ET: essential thrombocythemia; PV: polycythemia vera; PMF: primary myelofibrosis) are an infrequent group of blood cancers which arise from a CD34 + hematopoietic stem cell (HSC) in the bone marrow mainly due to driver mutations in JAK2, CALR or MPL. These alterations induce the transformation of normal cells into malignant ones, finally causing an overproduction of mature myeloid cells through multiple molecular mechanisms [1, 2].