Perianal Paget’s Disease with synchronous adenocarcinoma: An unusual diagnosis

We present a 45-year-old male Caucasian with a one-year history of perianal erythema resistant to topical corticosteroid and antifungal therapy. Physical examination of the perianal region revealed a painful, non-pruriginous erythema with erosions that involved all the circumference of the anus. No oral and no genital lesions were observed. Serologic and virologic markers were collected and a skin biopsy was performed. The markers turned out to be negative and the biopsy revealed the diagnosis of Perianal Paget Disease (PPD). Imunohistochemistry was positive for CK20, EMA and CEA, and negative for CK7. Digital rectal examination suggested a suspicious thickening in the rectum and colonoscopy revealed the presence of a vegetating mass of the distal rectum. Biopsies of the rectal mass displayed a well-differentiated invasive adenocarcinoma. The patient was proposed to neoadjuvant chemo and radiotherapy, followed by abdominoperineal resection with wide surgical excision and lymph node dissection. This case illustrates the importance and difficulties encountered in the clinical diagnosis of this rare disease.