Signet-ring Cell Carcinoma in Hyperplastic Polyp of the Stomach.

Signet-ring cell carcinoma rarely occurs in gastric hyperplastic polyps, with only a few such cases reported. We treated a 76-year-old woman with a signet-ring cell carcinoma arising from a hyperplastic polyp. She had been diagnosed with a gastric hyperplastic polyp four years previously. A follow-up endoscopic examination revealed the lesion in the polyp. A biopsy showed signet-ring cell carcinoma. Hybrid endoscopic submucosal dissection with snaring and a histological examination revealed signet-ring cell carcinoma in a hyperplastic polyp. The polyp was completely excised, with no evidence of recurrence one year later. A hyperplastic polyp of the stomach may transform into adenocarcinoma of an undifferentiated type.