To investigate the pathological features and effect of colorectal cancer with large bile duct metastases on postoperative recurrence.

Clinical data of 5 patients who were detected with space-occupying masses in the large bile ducts by imaging examination and pathologically diagnosed with colorectal cancer and large bile duct metastases admitted to Sun Yat-sen Memorial Hospital of Sun Yat-sen University from January 2016 to October 2020 were retrospectively analyzed. The informed consents of all patients were obtained and the local ethical committee approval was received. Among them, 4 patients were male and 1 female, aged from 48 to 59 years, with a median age of 54 years. Primary lesions were located in the left colorectum in 5 patients, complicated with liver parenchymal metastases, including 4 cases of multiple nodules and 1 case of single nodule. The expression levels of CK7, CK20 and CDX2 proteins were measured by HE staining and immunohistochemistry. Pathological features, diagnosis and treatments, and clinical prognosis of the patients were observed.

Among 555 patients with liver metastases from colorectal cancer, the incidence rate of large duct metastasis was 0.9%(5/555). Liver resection or lesion resection was performed according to the location of metastatic lesions. Pathological examination showed that the degree of differentiation of liver metastases was the same to that of primary lesions, including 4 cases of moderately-differentiation and 1 case of lowly-differentiation. The dilated large bile duct was filled with masses, and the histological morphology of bile duct metastases was the same as that of liver parenchymal metastases. The growth patterns of bile duct metastases consisted of intraductal polypoid growth, cancer cell growth along with the bile duct basement membrane and isolated extrahepatic bile duct metastasis. Immunohistochemical staining demonstrated that CK20 and CDX2 in the metastatic cancer cells were positive, whereas CK7 negative. The residual bile duct epithelium was positive for CK7, whereas negative for CK20 and CDX2. 3 cases recurred between postoperative 8 and 32 months.

Large bile duct metastasis from colorectal cancer is manifested with typical pathological morphology and biological behavior, which can spread along with the biliary tree in a continuous or discontinuous pattern. Definite diagnosis, anatomical resection of hepatobiliary ducts, complete removal of the involved bile ducts, and intimate postoperative monitoring are effective approaches to improve the patients' prognosis.