MPO and overlapping connective tissue disease: On the other hand, the clinical features of overlap syndrome (OvSD) of pSS with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) (OvSD/pSS/AAV), which is an infrequent type of pSS-related vasculitis, have been reported as follows: (i) a detection rate of ANCA positivity at 10% to 20% immunologically; (ii) a low proportion of patients reclassified as OvSD/pSS/AAV; (iii) the strong association between myeloperoxidase (MPO)-ANCA and reclassification as OvSD/pSS/AAV; (iv) the relatively high rate of kidney involvement; (v) the concomitant occurrence of pSS with AAV [8,9,10].