Expert consensus on pathological diagnosis of intrahepatic cholangiocarcinoma (2022 version)
image: Intrahepatic cholangiocarcinoma (iCCA) can originate from the large bile duct group (segment bile ducts and area bile ducts), small bile duct group (septal bile ducts and interlobular bile ducts), and terminal bile duct group (bile ductules and canals of Hering) of the intrahepatic biliary tree, which can be histopathological corresponding to large duct type iCCA, small duct type iCCA and iCCA with ductal plate malformation pattern, and cholangiolocarcinoma, respectively. The challenge in pathological diagnosis of above subtypes of iCCA falls in the distinction of cellular morphologies, tissue structures, growth patterns, invasive behaviors, immunophenotypes, molecular mutations, and surgical prognoses. For these reasons, this expert consensus provides nine recommendations as a reference for standardizing and refining the diagnosis of pathological subtypes of iCCA, mainly based on the 5th edition of the World Health Organization Classification of Tumours of the Digestive System.
Credit: Wen-Ming Cong, Yuan J, Han Wang, Jun Chen, Xin Zhang, Xia Sheng
Intrahepatic cholangiocarcinoma (iCCA) represents a formidable malignancy originating from the epithelial lining and peribiliary glands of the intrahepatic bile ducts, ranging from the secondary branches to the minutest bile ductules. It is characterized by the expression of markers specific to cholangiocytes. This neoplasm constitutes 10-20% of all primary liver cancers6 and 20-30% of cholangiocarcinomas. In the context of China, a study revealed that among 26, 684 cases of surgically excised primary hepatic malignancies, hepatocellular carcinoma and iCCA comprised 90.2% and 8.2%, respectively. From 2006 to 2015, the age-standardized incidence rates of iCCA in China exhibited a modest increase from 2.0 to 2.2 per 100, 000, with a notable rise in the demographic aged over 65 years, escalating from 3.4 to 4.5 per 100, 000. iCCA is notorious for its aggressive nature, with a 5-year survival rate post-curative surgical resection languishing below 50%.
The clinicopathological distinctions between iCCA and extrahepatic cholangiocarcinoma are pronounced. Historically, the diagnosis of iCCA was hampered by a lack of refined diagnostic modalities, attributable to its heterogeneous histological presentations and ambiguous criteria for subtype classification. Nonetheless, the past decade has witnessed significant strides in the pathological understanding of iCCA, with several advancements incorporated into the fifth edition of the World Health Organization (WHO) Classification of Tumours of the Digestive System. Despite these advances, there remains a need for refinement in the histological classification criteria, differential diagnosis of histological variants, selection of immunohistochemical markers, and identification of molecular targets to enhance practical application. To date, no comprehensive guidelines delineating the pathological subtype diagnosis of iCCA have been established. Recognizing that a consensus on histological subtype diagnosis can streamline the pathological evaluation of iCCA, thereby furnishing a detailed pathological foundation for tailored clinical management, a panel of Chinese experts has collaboratively developed the present consensus on the pathological diagnosis of iCCA.
This expert consensus delineates nine recommendations aimed at standardizing and refining the diagnostic process for iCCA pathological subtypes, primarily anchored in the fifth edition of the WHO Classification of Tumours of the Digestive System.
The diagnosis of histological subtypes should be central to the routine pathological evaluation of iCCA. A critical aspect of this evaluation is distinguishing between large duct type and small duct type iCCAs. To aid in histological subtyping, it is advisable to optimize and utilize a combination of immunohistochemical marker panels. Additionally, the detection of molecular targets and immunotherapy biomarkers should be guided by the specific histological subtype of iCCA. Pathological reports should comprehensively detail the main pathobiological characteristics of iCCA. It is also recommended to avoid using the diagnostic term "intrahepatic cholangiocellular carcinoma" when referring to iCCA.
In the pathological reporting of iCCA, it is crucial to include features associated with the risks of postoperative recurrence and metastasis to inform clinical treatment strategies. These features should encompass the gross type, histological subtype, immunophenotype, differentiation grade, microvascular invasion, biological behavior, surgical margin status, pathological tumor–node–metastasis stage, background liver disease, and other pertinent information. To enhance the consistency and accuracy of iCCA pathological diagnoses, the adoption of a standardized template for pathological diagnostic reporting is strongly encouraged.
Full text
https://www.xiahepublishing.com/2310-8819/JCTH-2023-00118
The study was recently published in the Journal of Clinical and Translational Hepatology.
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