Rare perianal extramammary Paget disease successfully treated using topical Imiquimod therapy

Paget’s disease, described by Sir James Paget in 1874 [1], is classified as mammary and extramammary subgroups. Extramammary Paget’s disease (EMPD) is a rare condition that is part of a spectrum of intraepithelial adenocarcinomas characterized by proliferation of apocrine cells called Paget cells, located in the basal layer of the skin and often can reach to the entire epithelium thickness [2]. EMPD incidence age is 50 to 80 with the peak age of incidence being 65 years [2]. EMPD of the vulva is most common accounting for up to 65% of cases while other areas affected include perianal area, male groin, scrotum, and axillae [2]. Perianal Paget’s disease (PPD) is a subgroup of EMPD, which is an uncommon intraepithelial neoplasm. The true incidence of the disease is difficult to estimate due to its rarity, but it is known to represent less than 1% of all anal diseases and 6.5% of all cases of Paget’s disease [3]. Although its etiology has never been definitively determined, there are two types of PPD, primary likely represents intra-epithelial neoplasm from an apocrine source, whereas secondary disease may represent “pagetoid” spread from an anorectal malignancy [4].

In Brazil, Tanaka et al. [5] reported 14 cases of EMPD, four of which involved women with disease in the vulvar, groin or perianal areas. Trindade et al. [6] reported a primary Brazilian PPD patient, which presented erythematous, itching and little bleeding. The staging tests were normal, without evidence of metastasis.

Imiquimod is an immune response modulating drug that targets toll-like receptors of dendritic and Langerhans cells, which results in the release of multiple cytokines and can directly induce apoptosis of transformed epithelial cells [7]. Imiquimod is a drug of choice for genital warts, vulvar and vaginal intraepithelial neoplasia, and actinic keratosis [8], and it has emerged as a promising drug for the treatment of vulvar and scrotal EMPD [91011]. However, the exact statistics for PPD treatment efficiency with Imiquimod have not been well described.

The aim of this study was to describe a case of PPD in Brazil, and the effectiveness of topical Imiquimod therapy.