Abstract
RATIONALE: Neuroendocrine neoplasms (NENs) originating from neuroendocrine cells occur in the thyroid, respiratory, and digestive systems, with Gallbladder Neuroendocrine Carcinoma (GB-NEC) accounting for only 0.5% of all NENs and 2.1% of gallbladder cancers. Due to its rarity, little is known about GB-NEC's clinical presentation and treatment. PATIENT CONCERNS: We report a case of a 52-year-old male presenting with acute upper right abdominal pain, leading to further investigation. DIAGNOSES: Initial diagnostic workup, including abdominal ultrasound and contrast-enhanced CT, suggested gallbladder malignancy. Post-surgical pathology confirmed GB-NEC, with immunohistochemistry supporting the diagnosis. INTERVENTIONS: The patient underwent radical cholecystectomy, followed by etoposide plus cisplatin chemotherapy. After disease progression indicated by CT, the patient received additional cycles of chemotherapy with cisplatin and irinotecan, plus targeted therapy with anlotinib and immunotherapy with paimiplimab. OUTCOMES: The patient showed a partial response to initial treatment. Subsequent liver biopsy confirmed NEC, consistent with small cell carcinoma. With continued treatment, the patient maintains a good survival status. LESSONS: GB-NEC is associated with poor prognosis, emphasizing the importance of early detection and multimodal treatment strategies. Our case underlines the potential benefit of a comprehensive treatment plan, including aggressive surgery and chemotherapy, with further research needed to standardize treatment for this rare condition.