We detected the presence of the eosinophilic granular protein eosinophilic peroxidase (EPX), anti–EPX-positive intact eosinophils, and degranulated eosinophilic granular proteins in pancreatic tissue sections of murine models and human PC biopsies, indicating the involvement of eosinophils in the development of several pathological characteristics of PC. Here, EPX is linked to pachyonychia congenita.