Unveiling the unprecedented - Very late brain metastasis in cholangiocarcinoma: A case report and comprehensive analysis

Rationale: Cholangiocarcinoma (CCA) frequently invades nearby lymph nodes, the liver, and lungs. The liver and lungs are also common anatomic sites for the first recurrence of CCA. However, metastasis to the brain is exceptionally rare. Patient concerns: A 79-year-old male patient who was diagnosed with distal CCA and underwent pylorus-preserving pancreaticoduodenectomy along with adjuvant chemotherapy 13-years ago visited the neurosurgery outpatient department. He complained of dysarthria and right leg weakness that had started 7 days previously. Diagnoses: Brain computed tomography (CT) showed a 32 mm × 28 mm mass in the left frontal lobe with peripheral ring enhancement and vasogenic edema. A tumor mass removal operation was performed, and pathological examination revealed metastatic adenocarcinoma. Immunohistochemistry analysis revealed negativity for thyroid transcription factor-1 and napsin A, and positivity for cytokeratin (CK)7, CK20, and CK19. Simultaneously, Chest CT, abdomen-pelvis CT and 18-Fluoro-deoxyglucose positron emission tomography showed only two small nodules in the left upper lung, with no evidence of locoregional recurrence in the abdominal cavity. Considering these CT, positron emission tomography-CT, and pathologic findings, very late recurrence of biliary tract cancer with brain and lung metastases was suggested. Interventions and outcomes: A therapeutic plan involving systemic chemotherapy with gemcitabine and cisplatin was proposed, but the patient refused further chemotherapy. Lessons: This case highlights the unpredictable nature of metastatic patterns in CCA, where brain metastasis occurs very late, preceding locoregional recurrence in the liver. This challenges conventional expectations and underscores the need for vigilant surveillance and consideration of atypical metastatic sites in long-term survivors of CCA.