Cytokeratin Subset Immunostaining in Rectal Adenocarcinoma and Normal Anal Glands Implications for the Pathogenesis of Perianal Paget Disease Associated With Rectal Adenocarcinoma

Abstract Context.—A large percentage of cases of perianal Paget disease are associated with an internal cancer, most commonly rectal adenocarcinoma. Immunostains for cytokeratin 7, cytokeratin 20, and gross cystic disease fluid protein 15 are useful in identifying cases associated with rectal adenocarcinoma. The Paget cells and rectal adenocarcinoma cells of these lesions typically have a cytokeratin 7+/cytokeratin 20+/gross cystic disease fluid protein 15− immunophenotype. It is not known whether rectal adenocarcinoma unassociated with perianal Paget disease has the same cytokeratin profile as rectal adenocarcinoma associated with perianal Paget disease. Objective.—To evaluate the immunohistochemical cytokeratin 7 and 20 profile of resected rectal adenocarcinoma unassociated with perianal Paget disease as well as that of normal anal glands from hemorrhoidectomy specimens. Design.—We performed immunohistochemistry for cytokeratins 7 and 20 on tissues from 30 cases of rectal adenocarcinoma unassociated wit...