Mohs micrographic surgery with melanoma antigen recognized by T cells 1 (MART-1) immunostaining for atypical intraepidermal melanocytic proliferation.

Background: The efficacy of Mohs micrographic surgery (MMS) for atypical intraepidermal melanocytic proliferation (AIMP) is unknown.

Objective: To ascertain the frequency of diagnostic change to melanoma (upstaging) and the frequency of local recurrence after MMS for AIMP. A secondary outcome was the frequency of subclinical spread (defined as the requirement for >1 stage of MMS to achieve tumor-free margins).

Methods: Retrospective, cross-sectional study of 223 AIMP (with 92.4% located on the head, neck, hand, foot, or pretibial leg) patients treated with MMS with melanoma antigen recognized by T cells 1 (MART-1) immunostaining.

Results: Upstaging to unequivocal melanoma in situ or invasive melanoma was identified in 18.8% (42/223) of all AIMP patients. The local recurrence rate was 0% (0/223) with a mean follow-up time of 2.7 years (998 days). Subclinical spread was present in 23.8% (53/223) of AIMP patients.

Limitations: Single site, retrospective design, observational study, lack of objective criteria to diagnose AIMP.

Conclusion: MMS with MART-1 immunostaining achieves excellent local control of specialty site AIMP and permits definitive removal of subclinical spread before reconstruction. The central debulking excision should be evaluated with formalin-fixed paraffin-embedded section staining, since a significant percentage of AIMP are reclassified as melanoma in situ or invasive melanoma.