5-aminolevulinic acid-induced fluorescence-guided margin mapping and slow Mohs surgery for localized extramammary...

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.

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.

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).

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.