Malignant gastric outlet obstruction: direct biopsy in the submucosal tunnel to obtain the diagnosis

A 59-year-old man presented with recurring early satiety for 1 year and postprandial vomiting for 2 months; he had also experienced weight loss of approximately 12 kg over the previous year. Gastroscopy showed food retention in the gastric cavity and an endoscope with a diameter of 8.9 mm could not be passed through the pylorus ([Fig. 1]). The mucosa of the pylorus appeared normal. A barium swallow showed delayed emptying of the stomach, with no filling defects or niches ([Fig. 2]). Abdominal computed tomography showed localized thickening of the gastric antrum, without enlargement of the lymph nodes ([Fig. 3]). Endoscopic ultrasonography (EUS) showed thickened muscularis propria at the pylorus ([Fig. 4]). Given the presumed diagnosis of hypertrophic pyloric stenosis, and after the patient had given informed consent, we performed peroral endoscopic myotomy (POEM) ([Video 1]).