A non-metastasizing neoplasm arising from the wall of the duodenum. The disease is benign duodenal neoplasm (MONDO_0006734, a Monarch Disease Ontology id). Also known as: benign duodenal tumor, benign duodenal tumour, benign neoplasm of duodenum, benign neoplasm of the duodenum, benign tumor of duodenum, benign tumor of the duodenum, benign tumour of duodenum, benign tumour of the duodenum.