Anorectal mucinous adenocarcinoma associated with latent perianal Paget's disease.

We report a case (63-yr-old man) of anorectal mucinous adenocarcinoma associated with perianal Paget's disease, found incidentally by pathologic examinations of the resected specimen. Paget's disease resided just distal to the anorectal adenocarcinoma. The area of Paget's disease was rather small. The epidermis containing Paget's cells was continuous with the anorectal adenocarcinoma, as if adenocarcinoma cells invaded directly into the epidermis. The Paget's cells were positive for neutral and acid mucus. Ultrastructurally, Paget's cells contained secretory granules, microvilli, and a few tight junctions, but lacked tonofilaments. The mucinous adenocarcinoma cells also showed histochemical and ultrastructural features that were similar to those of Paget's cells. These findings strongly suggest that the Paget's cells were derived from direct spread from the anorectal adenocarcinoma, in this case. Clinicians and pathologists should carefully examine the perianal epidermis in anorectal carcinoma, even if there are no clinical findings of perianal Paget's disease. The English literature is also reviewed briefly.