69-year-old man presents with melanoma in situ of the upper back. A biopsy on 6/15/2017 showed malignant melanoma at least in-situ. Excision with 5 mm margin and skin graft closure on 8/9/2017 found residual melanoma in situ with at 2-4 o’clock. Additional 4mm margin excision on 9-13-17 still found residual lesion at 1-3 o’clock margin. Mapping punch biopsies were performed, and were all negative. Additional crescent excision from 12 – 5 o’clock also found no residual melanoma in situ.
Indistinct margins of a melanoma in situ are a challenge as this case represents. We finally performed mapping biopsies prior to our third attempt at clearing this lesion. Should this case have been treated with mapping biopsies from the beginning? In hindsight, it should have. But other noninvasive modalities could have been utilized. These can be Wood’s light examination and dermoscopy. Both of these can be used as adjuncts to guiding either excision margins or mapping biopsies.