A 70-year-old man was admitted to our institution due to aggravation of blood-sugar level control and because an abdominal CT showed dilatation of the main pancreatic duct. Upper gastrointestinal endoscopy revealed a flat elevated tumor with central ulceration in the second portion of the duodenum. Subsequent duodenoscopy for a more detailed examination showed that the tumor had originated in the minor duodenal papilla. A biopsy specimen showed moderately differentiated adenocarcinoma. Endoscopic retrograde pancreatography via the major duodenal papilla revealed a slightly dilated main pancreatic duct and obstruction of the accessory pancreatic duct. Endoscopic ultrasonography showed a hypoechoic mass in the minor duodenal papilla with retention of the muscularis propria of the duodenum. These findings suggest that the tumor existed only to a limited extent in the minor duodenal papilla, and that the tumor did not infiltrate into the pancreas. For treatment, pylorus-preserving pancreatoduodenectomy was performed, and histological findings revealed a well-differentiated adenocarcinoma that originated in the minor duodenal papilla. Primary adenocarcinoma of the minor duodenal papilla is extremely rare. Our case is the first report of primary adenocarcinoma of the minor duodenal papilla at an early stage with no infiltration into muscularis propria of the duodenum and pancreas.
Adenocarcinoma/*pathology/ultrasonography ; Aged ; Endosonography ; Humans ; Male ; Pancreatic Ducts/*pathology/ultrasonography ; Pancreatic Neoplasms/*pathology/ultrastructure

Purpose: Determination of optimal treatment strategies for HER2-positive advanced gastric cancer (AGC) in randomized trials is necessary despite difficulties in direct comparison between trastuzumab deruxtecan (T-DXd) and nivolumab as third or later-line treatments. Materials and Methods: This single-institution, retrospective study aimed to describe the real-world efficacy and safety of T-DXd and nivolumab as ≥ third line treatments for HER2-positive AGC between March 2016 and May 2022. Overall, 58 patients (median age, 64 years;69% male) were eligible for the study (T-DXd group, n=20; nivolumab group, n=38). Results: Most patients exhibited a HER2 3+ status (72%) and presented metastatic disease at diagnosis (66%). The response rates of 41 patients with measurable lesions in the T-DXd and nivolumab groups were 50% and 15%, respectively. The T-DXd and nivolumab groups had a median progression-free survival of 4.8 months (95% confidence interval [CI], 3.3, 7.0) and 2.3 months (95% CI, 1.5, 3.5), median overall survival (OS) of 10.8 months (95% CI, 6.9, 23.8) and 11.7 months (95% CI, 7.6, 17.1), and grade 3 or greater adverse event rates of 50% and 2%, respectively. Overall, 64% patients received subsequent treatment. Among 23 patients who received both regimens, the T-DXd–nivolumab and nivolumab–T-DXd groups had a median OS of 14.0 months (95% CI, 5.0, not reached) and 19.3 months (95% CI, 9.5, 25.1), respectively. Conclusions T-DXd and nivolumab showed distinct efficacy and toxicity profiles as ≥ third line treatments for HER2-positive AGC. Considering the distinct features of each regimen, they may help clinicians personalize optimal treatment approaches for these patients.