Bulbar adenomas with advanced dysplasia are rare and difficult to resect due to limited access and the Brunner gland rich submucosa, which often lifts poorly with EMR.

A 70-year-old man was referred for a 25-mm sessile bulbar adenoma with suspected high-grade dysplasia. Underwater ESD was performed with a distal circumferential incision and deep submucosal dissection beneath the Brunner’s gland layer. Gradual saline immersion and dissection from 7 to 3 o’clock helped expose the correct plane.

En-bloc resection was completed in 80 minutes, with minor muscular injuries clipped. Histology confirmed high-grade dysplasia (pTis) with R0 margins, and follow-up was uneventful. This case supports the feasibility and curative potential of ESD for selected duodenal bulb lesions.