A 67-year-old female immigrant from India without significant medical history was initially evaluated in the emergency department with complaints of 2 months of progressive epigastric pain, early satiety, nausea, and recurrent emesis associated with a 5-kg weight loss. On physical examination, a firm epigastric mass was noted. Extensive circumferential thickening of the gastric antrum and pylorus accompanied by gastric distention, and the presence of a malrotated and dilated duodenum which was entirely located right of the midline was noted in the abdominal computed tomography (CT) report (Fig. 1). The patient was admitted to the hospital for expedited diagnosis. Esophagogastroduodenoscopy (EGD) demonstrated hypertrophic antral folds with hyperemia and friability, and a dilated proximal duodenum with an abrupt, angular transition point at the third segment (Fig. 2a, b). Numerous biopsies of the antrum and pylorus were interpreted as having extensive lymphocytic inflammatory cell infiltration, but no malignant cells. Endoscopic ultrasound (EUS) confirmed the presence of circumferential hypertrophy in the antrum consistent with suspected tissue invasion (Fig. 3). Following nasogastric tube gastric decompression, a naso-duodenal feeding tube was advanced past the area of antral obstruction. Due to ongoing signs of obstruction with continued intolerance to oral intake and a high suspicion for malignancy, exploratory laparotomy was performed. At operation, a hard and thick antral mass suggestive of malignancy was immediately visible, with white plaque overlying the gastric serosa, suggestive of malignant serosal invasion (Fig. 4a). When the stomach and transverse mesocolon were lifted, tumor invasion into the root of the mesentery and into the serosa of the third and fourth segments of the duodenum was apparent, tethering the third and fourth portions of the duodenum to the ligament of Treitz (Fig. 4b). There was no evidence of obvious metastatic disease. Resection was deferred given that the locally advanced nature of the tumor would have required a subtotal gastrectomy, en bloc extended right hemicolectomy, and en bloc resection of the third and fourth portions of the duodenum. Instead, a loop gastro-jejunostomy and a feeding jejunostomy were performed for nutritional support, and the abdomen was closed, leaving open the possibility of later resection after neo-adjuvant therapy. Biopsies of the invaded gastric mucosa demonstrated scattered dyscohesive clusters of cells exhibiting signet ring morphology which stained positively for CDX2, CK7, and CK20, providing support for a primary gastric cancer. The tumor cells were diffusely infiltrative and not densely aggregated as a mass, consistent with the diffuse thickening seen on laparotomy, which also helped to explain the difficulty in obtaining a tissue diagnosis at endoscopic biopsy. The patient recovered uneventfully from surgery, and began neo-adjuvant chemotherapy. R. J. Huang (&) A. M. Chen U. Ladabaum Department of Medicine, Stanford University Medical Center, Stanford, CA, USA e-mail: rjhuang@stanford.edu