GPC1 and pachyonychia congenita: GPC1+ circulating exosomes were significantly elevated in patients with PC (including carcinoma-in-situ, stage I–IV) compared to healthy individuals, indicating that it may act as an biomarker for all stages of PC and aid in distinguishing PC from benign pancreatic disease and healthy individuals, while CA 19–9 levels in the serum fail to distinguish patients with PC from those with benign pancreatic disease.