There was no significant difference between expression of STAT4 in PV skin lesion (19.37 ± 1.69) and the control group (18.59 ± 3.01; p > 0.05), as well as between PV skin lesions and PV perilesional skin (19.69 ± 3.23; p > 0.05). This evidence concerns the gene STAT4 and acquired polycythemia vera.