A case of Helicobacter pylori-negative gastric cancer associated with Cronkhite-Canada Syndrome.

A 43-year-old Japanese man diagnosed with Cronkhite-Canada Syndrome (CCS) underwent endoscopic submucosal dissection for Helicobacter pylori-negative gastric cancer. Histologically, the completely resected specimen showed large and small irregular glands composed of foveolar epithelial-like atypical cells, and it was immunohistochemically MUC5AC positive overall, MUC6 positive except for the surface layer and nearby parts, and MUC2 negative. The patient was diagnosed with gastric-phenotype, low-grade, well-differentiated adenocarcinoma. This is a case of gastric cancer developing in CCS definitively without H. pylori infection. We conclude that H. pylori infection is not an absolute condition in gastric cancer associated with CCS. Elucidation of the true malignant potential of CCS excluding the effects of H. pylori infection is needed.