Perianal Paget’s disease and malignancies of lower hindgut and anal canal

Perianal Paget’s disease (PPD) consists of a skin neoplasia which can be either primary or secondary to an underlying internal malignancy. Treatment of perianal Paget’s disease associated with primary colonic or anal adenocarcinoma is secondary to the treatment of the primary tumor and, thus, accurate clinical, pathological and immunohistochemical assessment is essential. Adenocarcinomas are estimated to be only 10% of anal cancer, and anal mucinous or colloid adenocarcinoma is an even rarer entity. We reviewed literature concerning the association between malignancies of the lower gastrointestinal tract and anal canal not associated with a chronic fistula-inano and perianal Paget’s disease, focusing on immunohystochemical differential diagnosis and management. Immunohistochemistry is very useful in choosing the ideal treatment for perianal Paget’ s disease; our “immunopanel” is useful to classify perianal Paget’s disease