Risk of tumor upstaging following partial biopsy and scouting biopsy in the treatment of melanoma in situ and invasive melanoma with Mohs micrographic surgery: a retrospective cohort study.

Understanding the impact of diagnostic and preoperative biopsy techniques on upstaging risk during treatment of melanoma in situ and invasive melanoma (MIS/IM) with Mohs micrographic surgery (MMS) is important for preoperative counseling and surgical planning. To determine the risk of tumor upstaging associated with partial biopsy and scouting biopsy techniques during MMS treatment of MIS/IM. A retrospective cohort study of 327 patients who underwent MMS for MIS/IM treatment at Dartmouth between March 2020 through January 2024. Binary logistic regression was used to assess the association of diagnostic and scouting biopsy with risk of upstaging. Seven (n = 7/327, 2.1%) patients upstaged during MMS, and four newly qualified for SLNB. Punch biopsy and partial biopsy were significantly associated with tumor upstaging. Upstaged tumors had greater number of MMS stages. Scouting biopsy use led to a 14.0% relative risk reduction in upstaging. A low overall risk of upstaging and SLNB following MMS validates recent data in the literature and supports use of MMS for MIS/IM treatment. As partial and punch biopsy contribute to upstaging risk, dermatologists should consider broad shave biopsies when sampling suspicious pigmented lesions. Preoperative scouting biopsies may be useful in reducing upstaging risk, number of MMS stages, and associated patient morbidity.