Primary signet-ring cell carcinoma of the extrahepatic bile duct: A case report

BACKGROUND: Signet ring cell carcinoma (SRCC) is a specific type of mucinous secretory adenocarcinoma, which contains abundant mucus in the cytoplasm and pushes the nucleus to one side of the cell membrane, forming a round or oval, and the nuclear deviations give the cells a signet ring-like appearance. SRCC often originates in the gastrointestinal tract, especially in the stomach. However, primary SRCC of the extrahepatic bile duct is extremely rare. Therefore, little is known about its epidemiology, treatment, and prognosis. CASE SUMMARY: An 82-year-old female was admitted with abdominal pain, jaundice, and skin pruritus for 2 mo. She had no specific family history. Physical examination presented normal vital signs, icteric sclera, visible jaundice, and mild tenderness in the right upper abdominal quadrant. Tumor-related cell markers were within normal values. Contrast-enhanced computed tomography revealed a thickened wall of the common bile duct, strengthened with intrahepatic bile duct dilation and multiple round-like lesions in the liver. In addition, the lymph nodes in the hepatic hilum area, the pancreatic head area, and around the abdominal aorta were enlarged. Thus, a preoperative diagnosis of cholangiocarcinoma was established. To alleviate jaundice and prolong the overall survival, percutaneous transhepatic cholangiopancreatic drainage (PTCD) was performed. During the operation, segmental stenosis of the extrahepatic bile duct and a vine-like expansion of the intrahepatic bile duct was observed. Furthermore, a biliary biopsy was performed under fluoroscopy to determine the nature and origin of the lesion. The pathological diagnosis of the biopsy was SRCC. Finally, a diagnosis of primary SRCC of extrahepatic bile duct with distant lymph node metastasis and multiple liver metastases was made based on the radiographic, PTCD, and pathological characteristics. The tumor was diagnosed as T3N1M1 stage IV. Despite our aggressive approach, the patient died of liver failure after 1 mo. CONCLUSION: This is the only case report on primary SRCC of the extrahepatic bile duct with distant organ metastasis to date.