Claudin 18.2 Expression in Cholangiocarcinoma: Clinicopathological Heterogeneity, Prognostic Significance, and Impact of Positivity Thresholds - Tugba Toyran; Kivilcim Eren Ates; Ferhat Can Piskin; Tolga Köşeci; Hatice Asoglu; Yusuf Kemal Arslan; Ugur Topal; Arbil Acikalin (Journal of Clinical Medicine, 2026)