Mohs surgery for female genital Paget's disease: a prospective observational trial.

BACKGROUND: Extramammary Paget's disease recurs often after traditional surgical excision. Margin-controlled surgery improves the recurrence rate for male genital disease but is less studied for female anatomy. OBJECTIVE: This study aimed to compare surgical and oncologic outcomes of margin-controlled surgery vs traditional surgical excision for female genital Paget's disease. STUDY DESIGN: We conducted a prospective observational trial of patients with vulvar or perianal Paget's disease treated with surgical excision guided by Mohs micrographic surgery between 2018 and 2022. The multidisciplinary protocol consisted of office-based scouting biopsies and modified Mohs surgery followed by surgical excision with wound closure under general anesthesia. Modified Mohs surgery cleared peripheral disease margins using a moat technique with cytokeratin 7 staining. Medial disease margins (the clitoris, urethra, vagina, and anus) were assessed using a hybrid of Mohs surgery and intraoperative frozen sections. Surgical and oncologic outcomes were compared with the outcomes of a retrospective cohort of patients who underwent traditional surgical excision. The primary outcome was 3-year recurrence-free survival. RESULTS: Three-year recurrence-free survival was 93.3% for Mohs-guided excision (n=24; 95% confidence interval, 81.5%-100.0%) compared to 65.9% for traditional excision (n=63; 95% confidence interval, 54.2%-80.0%) (P=.04). The maximum diameter of the excisional specimen was similar between groups (median, 11.3 vs 9.5 cm; P=.17), but complex reconstructive procedures were more common with the Mohs-guided approach (66.7% vs 30.2%; P<.01). Peripheral margin clearance was universally achieved with modified Mohs surgery, but positive medial margins were noted in 9 patients. Reasons included intentional organ sparing and poor performance of intraoperative hematoxylin and eosin frozen sections without cytokeratin 7. Grade 3 or higher postoperative complications were rare (0.0% for Mohs-guided excision vs 2.4% for traditional excision; P=.99). CONCLUSION: Margin control with modified Mohs surgery significantly improved short-term recurrence-free survival after surgical excision for female genital Paget's disease. Use on medial anatomic structures (the clitoris, urethra, vagina, and anus) is challenging, and further optimization is needed for margin control in these areas. Mohs-guided surgical excision requires specialized, collaborative care and may be best accomplished at designated referral centers.