Multiple 'serrated adenocarcinomas' of the colon with a cell lineage common to metaplastic polyp and serrated adenoma. Case report of a new subtype of colonic adenocarcinoma with gastric differentiation

A 70-year-old woman underwent right hemicolectomy and six carcinomas were r ecognized in the resected colon. These carcinomas were considered to be of a cell lineage common to serrated adenoma (SA) and hyperplastic (metaplasti c) polyp (H/MP), because of the occurrence of multiple SAs and H/MPs around the carcinomas, as well as the co-existence of SA and H/MP areas within th e carcinomas. These carcinomas had the following common histological and im munohistochemical features: a serrated structure resembling SA; a lace-like structure; infiltrative growth,within the muscularis propria, with dediffe rentiation at the invasive front; and immunohistochemical expression of pS2 and human gastric mucin, Based on these features, a new subtype of carcino ma is proposed, with a cell lineage common to SA and H/MP. It would also se em that p53 is involved in the serrated adenoma-carcinoma sequence. Copyrig ht (C) 2000 John Wiley & Sons, Ltd.