Diagnosis and Management of Duodenal Bulb Neuroendocrine Carcinoma with Liver Metastases: A Case Report and Literature Review.

Duodenal bulb neuroendocrine carcinoma (NEC), a subtype of neuroendocrine neoplasms (NENs), is a rare, high-grade malignancy often presenting at an advanced stage. We report a 40-year-old male with epigastric pain and melena who underwent a stepwise diagnostic and therapeutic protocol. Upper gastrointestinal endoscopy identified a 3.5 × 3.0 cm ulcerative lesion in the duodenal bulb, from which multiple deep biopsies were obtained to minimize the risk of misclassification, underscoring an essential educational point for clinical practice. Histopathological examination demonstrated poorly differentiated NEC with intravascular tumor thrombi, and immunohistochemical staining confirmed neuroendocrine differentiation (CgA, Synaptophysin, CD56, CK7) with a Ki-67 index of approximately 70%. Contrast-enhanced computed tomography (CT) revealed synchronous hepatic and lymph node metastases, establishing advanced disease. Following multidisciplinary evaluation, the patient received systemic chemotherapy with etoposide and cisplatin, administered in four cycles under routine monitoring of hematologic and hepatic parameters. Despite treatment, repeat CT demonstrated progressive hepatic lesions, culminating in hepatic failure and death. This protocol not only highlights the reproducible diagnostic workflow-endoscopic biopsy, immunohistochemical profiling, and cross-sectional imaging-but also serves an educational role in reminding clinicians of the diagnostic pitfalls inherent in superficial sampling and the necessity of deep biopsies for accurate classification. The case illustrates both the methodological steps required for accurate classification of duodenal NEC and the limitations of current treatment strategies. Our report contributes to the scarce data on duodenal bulb NEC and emphasizes the importance of early recognition, systematic diagnostic procedures, and multidisciplinary management to guide future practice.