Usefulness of Mapping Biopsy in the Treatment of Penoscrotal Extramammary Paget's Disease

Extramammary Paget's disease (EMPD) is a rare cutaneous malignancy; however, the standard treatment of EMPD has not been established. In this study, we applied mapping biopsy to penoscrotal EMPD and evaluated its effects. A retrospective chart review was performed to determine the outcomes of patients with primary penoscrotal EMPD who underwent surgery at our institution between 2007 and 2014. Patients were divided into two groups (one group underwent mapping biopsy, while the other group did not), and the difference between the two groups was analyzed. The 5-year tumor-free rate was estimated using the Kaplan-Meier method, and the risk factors for local recurrence were also estimated. A total of 44 patients were analyzed, and the mean follow-up of patients was 50.27 months. Patients who underwent mapping biopsy showed significantly lower tumor involvement at permanent and frozen biopsies and a lower local recurrence rate than those who did not undergo mapping biopsy. The 5-year tumor-free rate was significantly higher in the mapping biopsy group than in the non-mapping biopsy group. Multivariable analysis demonstrated that age at operation, mapping biopsy, and false-negative results at frozen biopsy were associated with local recurrence. Mapping biopsy is beneficial to reduce local recurrence in penoscrotal EMPD.