The case of a 34-year-old woman complaining of diarrhoea and abdominal pain is presented. Contrast radiography and endoscopy showed multiple polypoid tumours in the second part of the duodenum. Moreover, a severe fatty infiltration of the pancreas was shown by magnetic resonance and computed tomography scans. Due to pain, pancreatoduodenectomy (Whipple operation) was performed, and subsequent histopathologic examinations showed excessive Brunner gland hyperplasia of the duodenum and severe lipomatous atrophy of the pancreas. The occurrence of these two rare conditions in one patient has not been described previously, and it is conceivable that the lipomatous atrophy and exocrine insufficiency of the pancreas may have caused a compensatory stimulation of the submucosal structures of the duodenum.