The Role of the Mesopancreas in Periampullary Malignancies

Background: Surgery and the perioperative management for periampullary carcinomas are translated from the more frequent ductal adenocarcinoma of the pancreatic head (hPDAC). After implementation of the pathological circumferential resection margin (CRM), true margin negativity dropped dramatically for hPDAC patients. The frequent infiltration of the mesopancreas (MP) is a causative factor for incomplete resection. It remains unknown if the oncological relevance of the MP remains exclusive for the hPDAC or if it can be translated into the operative management for periampullary carcinomas as well. Material and methods: Patients who received oncological pancreatoduodenectomies (PD) for dCCAs and ACs from 2015 to 2025 at our department were included in this study (n =100). The MP status was retrieved from the histopathological reporting. Results: MP infiltration was evident in 36.4% and 62.2% of the AC and dCCA patients respectively (p = 0.015). Across both tumour entities, mesopancreatic involvement emerged as a marker of significantly worse overall survival (AC: p = 0.002; dCCA: p = 0.013). Conclusion: Distal cholangiocarcinomas presented with a frequent infiltration into the mesopancreas. A positive infiltration status of the MP significantly correlated with incomplete resection status in ampullary carcinoma. In addition, MP infiltration proved to be an adverse prognostic factor for overall survival in periampullary carcinoma patients, underscoring its potential role in perioperative staging and its possible relevance for surgical decision-making. This is the first study revealing insights into the infiltrative prevalence of the MP in periampullary carcinomas. Mesopancreatic involvement may not be exclusive to pancreatic cancer and warrants further investigation in other periampullary malignancies.