Extramammary Paget's disease: Our 15-year experience in a Southeast Asian population

The treatment of choice for Extramammary Paget's disease (EMPD) is wide excision. However, owing to the tendency of microscopic spread and multi-centricity of the disease, resection margins are hard to determine. Despite the use of adjunctive methods such as mapping biopsy and Moh's micrographic surgery, recurrence rates remain high. We aim to establish treatment guidelines by determining the variables associated with recurrence and the optimal resection margin size. We reviewed 52 patients who underwent wide excision in our institution between 2002 and 2017. A retrospective review of patient demographics, disease characteristics, and resection margins was performed. Most patients were Chinese (n = 39, 75%) male (n = 38, 73.1%). The mean tumor size was 6.73 cm (SD=4.10; range, 1.50-21.0 cm). The mean resection margin was 2.5 cm (SD=1.21; range, 0.20-5.50 cm). Eleven patients (21.2%) had disease recurrence. Nodal involvement significantly correlated with disease recurrence or mortality related to disease (HR=4.645; 95% CI=1.539,14.018; p = 0.0064). Subgroup analysis showed a significant correlation between resection margin size and recurrence rates (p = 0.047). We observed that a smaller resection margin (<2 cm) is acceptable for smaller tumor sizes (<6 cm) to achieve the lowest possible recurrence rates (20%), whereas a larger resection margin (>2 cm) is required for larger tumor sizes (>6 cm) (p = 0.012). Our results suggest that a resection margin recommendation can be made in correlation to the tumor size. This serves as a guideline for surgeons to predict the defect size and provide options for reconstructive surgery while achieving low recurrence rates.