Mohs Micrographic Surgery Design and Execution of Intermediate and Complex Closure

Mohs micrographic surgery (MMS) is a surgical technique designed for the precise removal of cutaneous cancers. MMS is characterized by en-face tissue processing, allowing complete peripheral and deep-margin assessment intraoperatively. This results in the highest possible cure rates for skin malignancies, including non-melanoma skin cancers and thin melanomas with immunohistochemical stains. In addition, MMS is a tissue-sparing technique that confirms negative histologic margins before defect reconstruction.

MMS was originally developed by Dr. Frederick E. Mohs and coined as chemosurgery. Formerly, tumors were fixed with zinc chloride in situ. After 1 day of fixation, the tumor was excised and histologically read for tumor clearance. If tumor burden was retained after initial excision, the process was repeated daily until pathologic clearance was attained. This process was time-consuming, involved serial visits over multiple days, and created a necrotic eschar at the excision site that did not allow for reconstruction. Modern MMS, popularized in the 1970s, utilizes fresh frozen section histology. This allows the entire procedure to be completed on the same day and avoids tissue damage to the defect site. As a result, Mohs defects can be repaired with various techniques ranging from linear closures to skin grafts and flaps on the same day as the Mohs procedure.

Mohs surgeons perform the majority of reconstructions at cosmetically and functionally sensitive sites. For a Mohs defect, the reconstructive ladder includes secondary intention healing, intermediate and complex linear repairs, split- or full-thickness skin grafts, local flaps, and interpolated flaps. Linear repair types include intermediate and complex closures. Both repair types are denoted with specific Current Procedural Terminology (CPT) criteria, and their definitions were revised in 2020. This recent CPT revision has resulted in a shift toward more intermediate closures and less complex closures being performed.