A 76-year-old man was referred to our hospital in 2014 with a duodenal tumor. Esophagogastroduodenoscopic (EGD) examination showed a pedunculated polypoid lesion in the 3rd portion of the duodenum, measuring 30 mm in size, with a nodular-appearing overlying mucosa. The lesion was white in color with a few areas of focal erythema. Based on its size and the mucosal appearance, the lesion was presumed to be cancerous or a tubulovillous adenoma with severe atypia. Endoscopic mucosal resection (EMR) was performed and unexpectedly resulted in a piecemeal mucosal resection. The resected specimen was observed to be a tubulovillous adenoma with severe atypia. Following EMR, he underwent an EGD every 6 months without any recurrence observed over 3 years. The complete resection rate is low with EMR of the duodenum, and regular EGD is necessary to assess the risk of local recurrence.
