Upstaging of melanoma in situ and lentigo maligna treated with Mohs micrographic surgery rarely results in additional surgical management.

As Mohs micrographic surgery (MMS) is more widely utilized for melanoma in situ (MIS) and lentigo maligna (LM), there is increasing concern over whether the procedure can negatively affect the treatment of upstaged tumors. Previous studies have shown that about 1-2% of MIS/LM treated with MMS require sentinel lymph node biopsy, but little is still known regarding surgical outcomes. We performed a retrospective chart review of 117 MIS/LM lesions treated with MMS at Brigham and Women's Hospital. We found a low rate of tumor upstaging (8.5% or 10/117), and only 1.7% (2/117) required wide local excision and sentinel lymph node biopsy. In both patients, there was successful location of the sentinel nodes by surgical oncologists. This study highlights the low risk of MIS/LM upstaging, with the majority changing to T1a, and the low need for further surgical management after MMS. Collaboration with other surgical specialties ensures appropriate management of patients with upstaged tumors.