Mural nodules and prevalence of high-grade dysplasia in branch duct intraductal papillary mucinous neoplasm of the pancreas undergoing resection.

Background: A mural module (MN) within a branch-duct intraductal papillary mucinous neoplasm (BD-IPMN) could be a potential target for local treatment. The main aim was to describe the location of the highest grade of dysplasia relative to the mural module to assess the relevance of local treatment.

Methods: Observational study of patients who underwent a pancreatic resection for suspected high-risk IPMN because of a mural module within a BD-IPMN (2012-2022). All patients had preoperative imaging confirming the enhancing mural module. The mural module was considered as a theoretical appropriate target for local destruction if no cancer or high-grade dysplasia (HGD) was described elsewhere than in the mural module.

Results: Eighty-two patients (male: 44 (54%); mean age: 65 ± 9.2 years) were included. The mean size of BD-IPMN containing the mural module was 32 ± 14.8 mm. The mural module mean diameter was 10.5 ± 5.6 mm, and the main pancreatic duct (MPD) mean diameter was 5.2 ± 3.6 mm. Six patients presented invasive carcinoma (7%), 37 had HGD (45%), and 39 (48%) had exclusively low-grade dysplasia. The mural module was dysplastic in 70 cases (85%). The mural module was considered a relevant target for local ablation in 45 patients (55%), whereas 37 patients (45%) had HGD/invasive carcinoma distant from the mural module. HGD was exclusively present in the mural module in 6/82 patients (7%). Factors independently associated with 'relevant indication for local treatment' were female gender (P = 0.004; OR = 5.2, 95% c.i. 1.7 to 15.9) and MPD < 5 mm (P < 0.0001; OR = 8.6, 95% c.i. 2.7 to 26.8).

Conclusion: In resected pancreata, BD-IPMN mural modules are associated with HGD distant from the mural module almost half of cases. The findings question the safety of local treatment, supporting pancreatectomy as the best approach.