Immunohistochemistry in intrahepatic cholangiocarcinoma: histological subtyping and drug selection.

Introduction: Since the release of the Methods: A thorough literature search was conducted using terms pertinent to the pathological diagnosis, histological subtyping, targeted therapy, and immunotherapy of iCCA. The content related to immunohistochemistry was summarized. Results: In the first part, we summarize the immunohistochemical markers for the histological subtype of iCCA (e.g., large duct type iCCA, small duct type iCCA), with a particular emphasis on their percentage of positive cases, expression location, and association with prognosis. Subsequently, a summary of the immunohistochemical markers for targeted therapy and immunotherapy of iCCA is performed, focusing on the consistency between immunohistochemistry and molecular detection, optimal clone, and prognostic significance. Conclusions: This review summarizes the critical role of immunohistochemistry in the pathological diagnosis of iCCA. It is noted that any diagnosis must be made by integrating comprehensive information. A pathological diagnosis merely based on immunohistochemical results is unreasonable. The development of subtype-specific and drug-targeted antibodies holds promise for refining iCCA precise diagnosis and therapeutic stratification.