我们报告了一例产生甲胎蛋白（AFP）的巨大十二指肠腺癌尸检病例。患者为70多岁的糖尿病男性。他以上腹痛为首发症状并转诊至我们医院。上消化道内窥镜和腹部计算机断层扫描显示十二指肠下行肢内有一直径为11厘米的肿瘤。病理活检显示为差分不明腺癌。尽管其癌胚抗原（CEA）和碳水化合物抗原19-9（CA19-9）水平在正常范围内，但其AFP水平显著升高（42,078.4ng/mL）。由于存在血管侵犯，手术切除并不可行，因此选择了化疗作为治疗选择。在胃空肠吻合术后，进行了一周期的改良卢科泼尼/5-氟尿嘧啶/奥沙利铂（mFOLFOX6）治疗。然而，该疗法未能奏效，患者的食欲逐渐恶化。最终，他因癌性消耗症的进展而逝世。尸检结果显示十二指肠癌长14厘米，主要位于十二指肠球部，直接侵犯了胃、胰腺和肝脏。病理学检查证实了差分不明的腺癌且产生AFP。十二指肠癌很少见，AFP产生的十二指肠癌更加罕见，目前只有包括我们自己在内的21例报告病例。我们报道了一例AFP产生的十二指肠腺癌尸检病例并回顾了相关文献中的病例。©2023年。日本胃肠学会。

We report an autopsy case of a large duodenal adenocarcinoma that produced alpha-fetoprotein (AFP). The patient was a man in his 70s with diabetes mellitus. He presented with epigastralgia and was referred to our hospital. Upper gastrointestinal endoscopy and abdominal computed tomography revealed a large tumor of 11 cm in diameter in the descending limb of the duodenum. A tumor biopsy showed poorly differentiated adenocarcinoma. Although his carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA19-9) levels were within the normal range, his AFP levels were significantly elevated (42,078.4 ng/mL). Due to vascular invasion, curative resection was not feasible, and chemotherapy was chosen as the treatment option. After gastrojejunostomy was performed to enable oral intake, one cycle of modified leucovorin/5-fluorouracil/oxaliplatin (mFOLFOX6) therapy was administered. However, it proved ineffective, and the patient's anorexia gradually worsened. Ultimately, he succumbed to the progression of cancer cachexia. Autopsy findings revealed a 14-cm-long duodenal carcinoma primarily located in the duodenal bulb, with direct invasion into the stomach, pancreas, and liver. A pathological examination confirmed a diagnosis of poorly differentiated adenocarcinoma with AFP production. Duodenal cancer is rare, and AFP-producing duodenal cancer is even rarer, with only 21 reported cases, including our own. We present this autopsy case of AFP-producing duodenal adenocarcinoma and review the cases reported in the relevant literature.© 2023. Japanese Society of Gastroenterology.