A case report of endoscopic submucosal dissection for a new subtype of gastric adenoma: mixed fundic and pyloric mucosa type

Precancerous lesions of gastric cancer are classified by the WHO (2019) into low-grade intraepithelial neoplasia and high-grade intraepithelial neoplasia (HGIN), and eminence lesions are adenomas. Gastric adenoma is a benign tumor of the stomach, which is more commonly located in the gastric antrum and gastric body. Usually, there is no obvious clinical manifestation. A 48-year-old man with intermittent abdominal bloating for four months to our hospital. Esophagogastroduodenoscopy revealed a 1.2 cm superficial elevated lesion in the anterior wall of the upper gastric body. The lesion had a whitish color and coarse surface. Biopsy revealed a low-grade intraepithelial neoplasia. Narrow-band imaging with magnifying endoscopy revealed a clear demarcation line with an irregular microsurface pattern. Detection of Helicobacter by the (13)C-urea breath test was positive. The patient underwent an endoscopic resection. Histological results revealed gastric adenoma with mixed fundic and pyloric mucosa type, with HGIN. The lesion contained three types of cells: pyloric gland, fundus gland and foveolar epithelium. Helicobacter pylori detection was negative in the lesion. The present case demonstrates a new histological subtype of gastric adenoma. To the best of our knowledge, this is the first case report of gastric adenoma with mixed fundic and pyloric mucosa cell types.