Mohs micrographic surgery and dermatopathology concordance: An analysis of 1421 Mohs cases over 17 years

Background: The success of Mohs micrographic surgery depends on the surgeon's ability to correctly interpret intraoperative frozen sections.

Objective: This retrospective study analyzed the rate of concordance between Mohs surgeons and dermatopathologists in reading slides from Mohs surgery cases.

Methods: A dermatopathologist reviewed all the frozen sections and the corresponding Mohs map for every 30th Mohs case at a practice employing 6 different Mohs surgeons during 2001-2017. Cases in which the dermatopathologist and the Mohs surgeon disagreed on the interpretation were noted.

Results: The concordance rate between Mohs surgeons and dermatopathologists was 99.79%. The 3 discordant cases included a case of squamous cell carcinoma, a case of superficial basal cell carcinoma, and a case of hypertrophic squamous cell carcinoma in situ.

Limitations: This analysis is limited to fellowship-trained Mohs surgeons and, therefore, might not be applicable to all physicians who perform Mohs.

Conclusion: Fellowship-trained Mohs surgeons show high concordance with board-certified dermatopathologists in the accurate and precise interpretation of histology slides in the setting of Mohs micrographic surgery.