PRKACB and cholangiocarcinoma: The third form is (iii) distal CCA (dCCA), the second most common form of CCA (20–30% of CCA cases), while the two extrahepatic CCA types commonly present a different molecular background than iCCA, including PRKACA-PRKACB fusions and mutations of ELF3 and ERBBE genes [4,5].