A rare indolent neuroendocrine tumor of the left intrahepatic bile duct: a case report emphasizing early detection.

Introduction: Neuroendocrine tumors (NETs) have traditionally been considered rare; however, an increasing incidence has been observed in recent years. Although often indolent, these tumors can exhibit malignant behavior. Our case of a left intrahepatic duct NET in a young woman highlights this rare presentation and underscores the need for heightened clinical awareness. Case Presentation: A 32-year-old woman presented with pruritus, jaundice, and mild elevations in liver enzymes. Imaging revealed a 40 × 33 mm mass in the vicinity of the left bile duct, in segment 4 of the liver. Octreotide scintigraphy confirmed the lesion as primary, and biopsy demonstrated a grade II well-differentiated NET. She underwent left hepatectomy with Roux-en-Y hepaticojejunostomy and lymphadenectomy. Postoperative recovery was uneventful except for mild atelectasis, which resolved with supportive care; she was discharged on postoperative day 8. Discussion: Primary intrahepatic bile duct NETs are extremely rare and may originate from biliary neuroendocrine cells or pluripotent stem cells. They often present with nonspecific symptoms such as jaundice or pruritus and can mimic cholangiocarcinoma. In this case, the tumor arose from the left intrahepatic bile duct without evidence of metastasis. Advanced imaging modalities, including magnetic resonance imaging, magnetic resonance cholangiopancreatography, and diffusion-weighted imaging, were crucial for diagnosis and surgical planning. Conclusion: Primary intrahepatic bile duct NETs are rare, present with nonspecific features, and require a multimodal diagnostic approach, with surgical resection offering favorable outcomes for localized, well-differentiated lesions.