Mohs Micrographic Surgery After Previous Nonsurgical Treatment in Basal and Squamous Cell Carcinoma: A Scoping Review of Diagnostic Challenges.

BACKGROUND: Mohs micrographic surgery (MMS) is a precise, tissue-sparing technique for the treatment of cutaneous malignancies. Diagnostic challenges after previous non-MMS treatments have been described in the literature but remain variably characterized. OBJECTIVE: To review published diagnostic challenges encountered during MMS for basal and squamous cell carcinomas after non-MMS treatments. MATERIALS AND METHODS: A scoping review was conducted using PubMed, MEDLINE Scopus, and Wiley Online Library, in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines extension for Scoping Reviews 2020. Extracted data included patient demographics, primary tumor and location, previous non-MMS therapies, depth of tumor invasion, intraoperative diagnostic challenges, and subsequent management. RESULTS: Thirty-eight studies comprising 93 patients (ages 2-92 years) met the inclusion criteria. Fourteen diagnostic challenges were reported, most commonly scarring masking residual tumor (n = 3, 21.4%) and verrucous carcinoma (n = 2, 21.4%). CONCLUSION: Previous non-MMS therapies may complicate MMS by introducing diagnostic ambiguity. These diagnostic challenges highlight variability in reporting and emphasize the need for standardized characterization of MMS specimens in previously treated tumors. Future studies using prospective or multicenter cohort designs are needed to better define the frequency and clinical relevance of these observations in modern practice.