Perianal and Vulvar Extramammary Paget Disease: A Report of Six Cases and Mapping Biopsy of the Anal Canal.

Treatment of perianal and vulvar extramammary Paget disease (EMPD), rare intraepithelial malignancies, is often challenging because of its potential to spread into the anal canal. However, there is still no consensus regarding the optimal resection margin within the anal canal. Between 2004 and 2014, six patients (three with perianal EMPD and three with vulvar EMPD) in which the spread of Paget cells into the anal canal was highly suspected were referred to our department. To evaluate the disease extent within the anal canal, preoperative mapping biopsy of the anal canal was performed in five out of six patients. Two patients were positive for Paget cells within the anal canal (one at the dentate line and the other at 0.5 cm above the dentate line), whereas in three patients, Paget cell were present only in the skin of the anal verge. Using 1 cm margin within the anal canal from the positive biopsy sites, we performed anal-preserving wide local excision (WLE), and negative resection margins within the anal canal were confirmed in all five patients. The remaining one patient with perianal EMPD did not undergo mapping biopsy of the anal canal because preoperative colonoscopy revealed that the Paget cells had spread into the lower rectum. Therefore, WLE with abdominoperineal resection was performed. During the median follow-up period of 37.3 months, no local recurrence was observed in all patients. Our small case series suggest the usefulness of mapping biopsy of the anal canal for the treatment of perianal and vulvar EMPD.