Pancreatic metastasis from gastric adenocarcinoma: a rare clinical entity and therapeutic challenges.

Introduction: Pancreatic metastases from gastric adenocarcinoma are exceptionally rare and often present diagnostic and therapeutic challenges. Their nonspecific clinical and radiological features make differentiation from primary pancreatic tumors particularly difficult, underscoring the need for a multidisciplinary approach. Case presentation: We report the case of a 54-year-old man who was initially treated in 2023 for gastric antral adenocarcinoma with independent cells. He underwent perioperative EOX chemotherapy followed by subtotal gastrectomy with Finsterer reconstruction and D2 lymphadenectomy (pT3N1). After 18 months, he developed a lesion of the pancreatobiliary junction with elevated CA 19-9 (192 U/mL). Biopsies were inconclusive, and a pancreaticoduodenectomy was performed in July 2025, preserving the gastrojejunostomy and creating a pancreaticojejunostomy on a Roux-en-Y loop. The postoperative course was complicated by a Grade B pancreatic fistula, bleeding requiring embolization of the gastroduodenal artery stump, and a superinfected hematoma requiring drainage, irrigation, and aspiration. On day 53, the patient was clinically stable with regression of the collections. Final pathology confirmed pancreatic and duodenal infiltration by independent-cell adenocarcinoma consistent with a gastric origin, with 8/12 positive lymph nodes and negative margins. Adjuvant chemotherapy was recommended after multidisciplinary discussion. Conclusion: This case illustrates the rarity of pancreatic metastasis from gastric adenocarcinoma and highlights the importance of multidisciplinary discussion in the management of such uncommon presentations.