Highlights
Non-ampullary duodenal adenomas rarely show malignant potential.
There is no evidence-based guideline regarding treatment of duodenal adenoma.
Non-ampullary adenomas can have malignant potential when the tumor is large and red.
When the duodenal cancer located periampullary area, PD is usually indicated.
HLPPSD is useful for duodenal periampullary early-stage cancer compared to PD.