Background: Perianal Paget's disease (PPD) is a rare intraepithelial adenocarcinoma of the anal margin. Primary PPD likely represents intra-epithelial neoplasm from an apocrine source, whereas secondary disease may represent "pagetoid" spread from an anorectal malignancy.
Case presentation: Histologic CDX-2 and CK20 are hallmark markers for colorectal-derived Paget's cells. Interestingly, our primary PPD patient presented both positive and no internal malignancy was identified. In addition, a negative CK7 marker was observed in our case in contrast with previously reported. Surgical excision is the standard treatment; however, previous studies have demonstrated good response with Imiquimod 5% cream in patients with vulval extramammary Paget disease (EMPD). The efficiency of Imiquimod treatment for PPD has not been well described. Our PPD patient was successfully treated using Imiquimod 5% cream.
Conclusions: This study describes a primary cutaneous PPD patient CDX-2+/CK20+/CK7- without invasion of the dermis and no associated colorectal carcinoma effectively treated using topical Imiquimod therapy, suggesting that Imiquimod might potentially be considered as a first-line treatment for PPD.
Keywords: Differential diagnosis; Histological markers; Perianal Paget’s disease; Topical Imiquimod therapy.