A woman in her 40 s was diagnosed with celiac disease after a decade-long history of abdominal pain and abnormal bowel movements. We compared villous atrophy in the duodenal bulb (DB) and descending duodenum (DD) using endoscopic and histopathological findings. Endoscopy revealed villous loss, a fine granular pattern, and groove-like depressions in the DD that were clearly visualized under narrow-band imaging (NBI) magnification. Histopathological examination revealed villous loss, crypt elongation, and hyperplasia. In contrast, endoscopy revealed a mosaic pattern in the DB, and NBI revealed circular or oval glandular openings surrounded by wide marginal crypt epithelium. Histopathology revealed gastric-type foveolar metaplasia (GFM) associated with the Brunner's glands. The DB and DD exhibited distinct endoscopic features, with GFM in the DB likely resulting from damage to the small intestinal mucosa. Since Brunner's glands are abundant in the DB, GFM may develop; thus, villous atrophy may be more difficult to appreciate endoscopically in the DB than with the clearer image in the DD. Recognizing regional differences in endoscopic appearance is crucial for the accurate diagnosis of celiac disease and other causes of duodenal villous atrophy.