Local recurrence of non-lentigo maligna melanoma in situ and safety excision margins: A systematic review.

The strength of evidence supporting a 2-step wide local excision (WLE) with 5 mm safety margins for melanoma in situ non-lentigo maligna (non-LM) type, compared with narrower margins, is unclear. This review aims to compare the frequency of local recurrence (LR) with different safety margins, after the complete surgical excision (R0) of non-LM MIS. We performed a systematic literature search in PubMed, Scopus, and the Cochrane Library up to March 17, 2024. The PRISMA checklist was used. Of 3,047 articles retrieved, seven retrospective studies were included, enrolling a total of 1,526 non-LM MIS cases excised with clear safety margins, after WLE (6 studies) or Mohs surgery (1 study). Most non-LM MIS were located on the trunk/extremities (68%-100%). Narrower margins were used in four studies, ranging from no WLE to 4 mm, and there was only one LR. Standard or wider margins were used in the remaining three studies reporting only two LR. The median follow-up ranged from 48 months to 6.6 years. The overall certainty and quality of evidence were very low. These findings of our systematic review highlight that current guidelines recommending the re-excision for non-LM MIS with clear initial margins lack strong evidence in support of this practice.