There are several instances in which the DCH is not followed in PV/PF, including (i) the presence of anti-Dsg antibodies without clinical disease (30), (ii) the absence of anti-Dsg1 or -3 antibodies in active disease (8, 9, 31), (iii) cases in which there is a mismatch of anti-Dsg levels and lesion type according to DCH postulates (10, 32), and (iv) the presence of cutaneous only PV (11, 33). Here, DSG1 is linked to acquired polycythemia vera.