Diffuse large B-cell lymphoma in the liver accompanied by primary biliary cholangitis: A rare and difficult-to-diagnose tumor with portal venous thrombosis

INTRODUCTION AND IMPORTANCE: The most common liver malignancies are hepatocellular carcinoma, intrahepatic cholangiocarcinoma, and metastatic tumors. Hepatocellular carcinoma and intrahepatic cholangiocarcinoma may invade the portal vein (PV). An association between diffuse large B-cell lymphoma (DLBCL) and primary biliary cholangitis (PBC) remains unclear. We herein report a thought-provoking case of a difficult-to-diagnose liver tumor with PV thrombosis in a PBC patient. PRESENTATION OF CASE: A 66-year-old woman had PBC, systemic sclerosis, diabetes, and osteoporosis. A solitary liver tumor accompanied by macrovascular thrombosis in the PV was detected incidentally. Based on dynamic imaging findings, we considered the tumor to be intrahepatic cholangiocarcinoma, and right lobectomy with lymphadenectomy was performed. Unexpectedly, pathological assessment made a definitive diagnosis of DLBCL that did not invade the vessels and bile duct. In fluorine-18-fluorodeoxyglucose positron emission tomography, abnormal accumulations were clearly observed in the breast tissue and peritracheal, parasternal, mediastinal, and pericardial lymph nodes. The patient achieved complete remission after systemic chemotherapy, and there has been no recurrence 3 years after surgery. CLINICAL DISCUSSION: Primary lymphoma in the liver is rare, and we did not consider our patient's tumor as primary liver lymphoma. Our case actually showed no tumor thrombosis in the PV. Although autoimmune disorders may increase the risk of non-Hodgkin's lymphoma, an association between DLBCL and PBC is still unclear, and we must remember that DLBCL may develop rarely in a PBC patient. CONCLUSION: Our case report provides a timely reminder for clinicians and surgeons in the fields of hepatology and hematology.