An Appraisal of Immunohistochemical Stain Use in Hepatic Metastasis Highlights the Effectiveness of the Individualized, Case-Based Approach: Analysis of Data From a Tertiary Care Medical Center

Intrahepatic cholangiocarcinoma: Insights on molecular testing, targeted therapies, and future directions from a multidisciplinary panel

Biliary tract cancers (BTCs) are a histologically and molecularly diverse group of malignancies arising from the gallbladder and the ductal epithelium of the biliary tree. Intrahepatic cholangiocarcinoma (iCCA) is the second most common primary liver malignancy in the United States. Surgical resection with negative margins is the only recognized curative treatment option for iCCA; however, most patients will present with advanced or unresectable disease. The clinical presentation is largely non-specific, with the characteristic symptoms of biliary malignancies being less frequent than extrahepatic cholangiocarcinoma. Clinical management in iCCA is heavily influenced by the molecular profile of individual tumors. Hence, pathologists must exercise caution to prevent tissue exhaustion during the diagnostic workup of iCCA and ensure the availability of tissue samples for molecular testing. Establishing standardized procedures for obtaining adequate tissue and using molecular testing is vital. Circulating tumor DNA (ctDNA) offers a potential alternative to tissue-based analysis, especially in cases with insufficient tissue samples. Drugs targeting alterations in NTRK, IDH1, BRAF, FGFR2, and HER2 are commonly utilized. Targeting the MDM2-p53 pathway represents an avenue for future investigations in advanced BTCs. Liver transplantation and locoregional therapies are treatment modalities that may represent curative intent treatments for patients with unresectable disease, and larger explorations are warranted. Akin to HCC, a multidisciplinary team-based approach is essential for patients with BTCs. Through this narrative review of literature, we provide an overview of the current management of iCCA with perspectives regarding future directions in the clinical management of iCCA. We also present patient perspectives regarding the importance of patient advocacy and access to advances in clinical research for patients with BTCs.

Cholangiocarcinoma: Pathologic and Molecular Classification in the Era of Precision Medicine

CONTEXT.—

Cholangiocarcinoma (CCA) is a heterogeneous cancer of the bile duct, and its diagnosis is often challenging.

OBJECTIVE.—

To provide insights into state-of-the-art approaches for the diagnosis of CCA.

DATA SOURCES.—

Literature review via PubMed search and authors' experiences.

CONCLUSIONS.—

CCA can be categorized as intrahepatic or extrahepatic. Intrahepatic CCA is further classified into small-duct-type and large-duct-type, whereas extrahepatic CCA is classified into distal and perihilar according to site of origin within the extrahepatic biliary tree. Tumor growth patterns include mass forming, periductal infiltrating, and intraductal tumors. The clinical diagnosis of CCA is challenging and usually occurs at an advanced tumor stage. Pathologic diagnosis is made difficult by tumor inaccessibility and challenges in distinguishing CCA from metastatic adenocarcinoma to the liver. Immunohistochemical stains can assist in differentiating CCA from other malignancies, such as hepatocellular carcinoma, but no distinctive CCA-specific immunohistochemical profile has been identified. Recent advances in next-generation sequencing-based high-throughput assays have identified distinct genomic profiles of CCA subtypes, including genomic alterations that are susceptible to targeted therapies or immune checkpoint inhibitors. Detailed histopathologic and molecular evaluations of CCA by pathologists are critical for correct diagnosis, subclassification, therapeutic decision-making, and prognostication. The first step toward achieving these goals is to acquire a detailed understanding of the histologic and genetic subtypes of this heterogeneous tumor group. Here, we review state-of-the-art approaches that should be applied to establish a diagnosis of CCA, including clinical presentation, histopathology, staging, and the practical use of genetic testing methodologies.