Mohs micrographic surgery histopathology concordance

BackgroundThe low recurrence rate and tissue-sparing benefit associated with Mohs micrographic surgery (MMS) requires accurate interpretation of frozen sections by the MMS surgeon.ObjectiveWe sought to assess concordance between dermatopathologists and MMS surgeons when reporting cutaneous malignancy in the MMS setting.MethodsThis study is a retrospective analysis of 1156 slides submitted during 10 years as part of a pre-existing randomized, blinded, quality assurance protocol. Slides were read by one of 5 dermatopathologists and represent cases from 3 MMS surgeons and 5 MMS fellows. Agreement or disagreement was recorded.ResultsOf the 1156 slides, 32 slides (2.8%) were disparate. Aside from differences regarding intraepidermal neoplasia, the concordance rate was 99.7%.LimitationsThis study represents data collected at a single institution in the United States alone.ConclusionThere was statistically significant concordance between MMS surgeons and dermatopathologists in frozen section interpretation in the MMS setting. Discordance was primarily related to the interpretation of in situ malignancy.