DSG1 and acquired polycythemia vera: Pemphigus vulgaris (PV) is a very rare chronic bullous disease (1:1,000,000) which typically occurs in patients aged between 45 and 65 years, and it is characterized by the formation of autoantibodies, mainly of the IgG class, directed against desmoglein-1 and desmoglein-3 (Dsg1 and Dsg3 protein) [1].