A first case of primary gastric verrucous carcinoma with isolated squamous epithelium in the stomach

Primary gastric squamous cell carcinoma (SCC) is a rare histological subtype of gastric cancer. Here, we report the first case of primary gastric verrucous carcinoma (VC), a well-differentiated variant of SCC. Gastroscopy revealed a papillary polypoid lesion at the posterior wall of the upper gastric body and isolated squamous epithelium at the greater curvature of the fornix in a 78-year-old woman. Endoscopic submucosal dissection was performed. Microscopically, the lesion comprised very well-differentiated squamous epithelium with minimal atypia and exhibited coarse papillary structure and bulbous epithelial downgrowth with submucosal invasion. Conventional SCC or adenocarcinoma components were not included, and the lesion was surrounded by the metaplastic intestinal mucosa. Human papillomavirus infection was not detected. Although the pathogenesis of primary gastric SCC remains controversial, here, the disease is suggested as having originated from squamous epithelium. Knowledge of primary gastric VC and difficulty in diagnosing it using surface biopsy is necessary.