Perianal Paget's disease: one century later and still a challenge.

Perianal Paget disease (PPD) is a rare neoplastic condition defined by the presence of atypical Paget cells in the perianal skin, the aetiology of which remains largely unknown. It can be divided in primary forms, arising as an intraepithelial disease or manifestation of an underlying skin adenocarcinoma or secondary forms resulting from epidermotropic spread or metastasis of a concealed carcinoma. Indeed, because of its rarity, clear options regarding the treatment of these patients are yet to be clarified. A high level of suspicion is needed whenever dealing with any unhealed perianal skin lesions and, therefore, the need for close long-term follow-up must be highlighted. Herein, two cases of PPD, one primary and another secondary, treated at the same institution, are presented in an attempt to document the involved complexity and to bring further insight into the understanding of this entity.