CD34 and myelofibrosis: Indeed, the above mentioned studies showed that prePMF patients (irrespective of their age) had higher leukocyte and platelet count, lower hemoglobin value, higher serum LDH, higher circulating CD34+ cells and higher frequency of palpable splenomegaly, when compared to ET ones; survival rates, leukemic transformation and rates of progression to overt myelofibrosis were different as well, being significantly worse for prePMF patients, thus underlining that a careful and proper diagnosis bears prognostically relevant information.