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.