Diagnostic challenges and therapeutic strategies for large-cell neuroendocrine carcinoma of extrahepatic bile ducts: A rare case report.

RATIONALE: Large-cell neuroendocrine carcinoma (LCNEC) of the extrahepatic bile duct (EHBD) is an exceedingly rare malignancy with few documented cases, presenting significant diagnostic and therapeutic challenges. This case highlights the complexities in managing this aggressive tumor, the essential role of multidisciplinary collaboration, and the ongoing debates regarding the necessity of adjuvant therapy. It underscores the need for biomarker-guided strategies.

PATIENT CONCERNS: A 75-year-old male presented with a 2-week history of jaundice, pruritus, dark urine, nausea, and vomiting. Laboratory findings revealed severe cholestasis, with a total bilirubin level of 179.2 μmol/L, and elevated CA19-9, measured at 457.36 U/mL.

DIAGNOSES: Abdominal magnetic resonance imaging revealed a 1.4 cm hilar bile duct mass with malignant characteristics. Postoperative histopathological analysis confirmed a 1.5 cm tumor consisting of 90% poorly differentiated LCNEC, with a Ki-67 index of 80% and a PD-L1 combined positive score of 5. The tumor exhibited vascular invasion, neural infiltration, and metastasis to 2 lymph nodes.

INTERVENTIONS: A multidisciplinary team (MDT) directed preoperative biliary drainage and performed a laparoscopic radical resection. Despite the presence of high-risk features, the patient declined adjuvant chemotherapy.

OUTCOMES: Six months post-surgery, an enhanced abdominal magnetic resonance imaging scan revealed intrahepatic metastases. Consequently, the patient commenced chemotherapy with a combination of cisplatin and etoposide.

LESSONS: This case underscores the aggressive nature of LCNEC of the EHBD and the crucial role of MDT-driven surgical intervention. The rapid recurrence suggests the necessity for postoperative adjuvant therapy; however, standard treatment protocols are lacking due to insufficient evidence from evidence-based medicine, highlighting the need for biomarker-driven strategies. The rarity of these tumors renders standardized management elusive, necessitating global collaboration to refine diagnostic and therapeutic frameworks.