Epitope spread phenomenon can be described as a process resulting in tissue damage which leads to the exposal of immunologically hidden certain protein components to the immune system evoking a secondary autoimmune response.9, 20 In PV, both intramolecular epitope spreading, leading to recognition of multiple epitopes within Dsg3, as well as intermolecular epitope spreading, from Dsg3 to Dsg1, have been shown to occur. Here, DSG1 is linked to acquired polycythemia vera.