Some proteins present in serum EVs, such as ficolin-2 (FCN2), inter-alpha-trypsin inhibitor heavy chain H4 (ITIH4) and fibrinogen gamma chain (FIBG), displayed better diagnostic values than CA19-9 (a non-specific tumor marker for the diagnosis of CCA) in the differential diagnosis between CCA (stage I-II) and PSC (90). The gene discussed is FCN2; the disease is cholangiocarcinoma.