5-aminolevulinic acid-induced fluorescence-guided margin mapping and slow Mohs surgery for localized extramammary paget disease: A retrospective exploratory comparative study.

OBJECTIVE: Extramammary Paget disease (EMPD) often extends beyond its clinically visible borders, making surgical margin control difficult, particularly in anatomically sensitive regions. This retrospective exploratory study compared 5-aminolevulinic acid (5-ALA)-induced fluorescence-guided margin mapping with slow Mohs surgery for localized EMPD, with emphasis on final margin clearance, treatment-process efficiency, tissue preservation, reconstruction requirement, patient-reported satisfaction, and crude recurrence proportion.

METHODS: We retrospectively reviewed 60 patients with biopsy-confirmed localized EMPD treated between January 2021 and June 2025. Patients underwent either ALA fluorescence-guided surgery (n = 32) or slow Mohs surgery (n = 28). In the ALA fluorescence-guided group, 20% 5-ALA cream was applied topically for 3 h before surgery, and fluorescence-positive borders were visualized using 405-nm excitation light. The planned surgical margin was placed 1 cm beyond the outer fluorescence-positive border into fluorescence-negative skin. Slow Mohs surgery was performed using staged paraffin-section histopathological assessment until negative margins were achieved. The primary endpoint was feasibility of final histopathological margin clearance. Secondary endpoints included first-pass positive margin rate, treatment-process duration, hospital stay, defect-to-visible-lesion area ratio, flap/graft repair rate, wound complication rate, patient-reported satisfaction, and crude recurrence proportion.

RESULTS: Final negative margins were achieved in all patients. In the ALA fluorescence-guided group, 3 patients had first-pass positive margins, yielding a first-pass positive margin rate of 9.3% (3/32); all three achieved negative margins after additional excision. Compared with the slow Mohs group, the ALA fluorescence-guided group had a shorter treatment-process duration indicator (112.25 ± 9.34 min vs 2.42 ± 0.22 days, P < 0.001), a lower defect-to-visible-lesion area ratio (1.42 ± 0.10 vs 1.90 ± 0.07, P < 0.001), a lower flap/graft repair rate (28.1%vs 75.0%, P = 0.0008), and higher exploratory patient-reported satisfaction scores (8.24 ± 0.68 vs 7.26 ± 0.39, P < 0.001). Crude recurrence proportions were 12.5% in the ALA fluorescence-guided group and 10.7% in the slow Mohs group (P = 1.000).

CONCLUSION: ALA-induced fluorescence-guided margin mapping may serve as a tissue-sparing adjunct within a pathology-driven surgical strategy for selected patients with localized EMPD. In this exploratory cohort, it was associated with shorter treatment-process duration, smaller relative defects, lower reconstruction requirement, and higher exploratory patient-reported satisfaction. These findings should not be interpreted as evidence of oncologic equivalence to slow Mohs surgery. Prospective studies with standardized recurrence-time assessment are needed to determine long-term oncologic durability.