Mohs Micrographic Surgery

In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan.


Mohs micrographic surgery is a tissue-sparing, precise method of skin cancer removal named in honor of the surgeon who developed the technique, Frederick Mohs. It is a surgical approach that offers high cure rates for the treatment of a variety of skin cancers, including basal cell carcinomas (BCC) and squamous cell carcinomas (SCC). The main advantage of Mohs surgery is that it offers precise microscopic control of the entire tumor margin while maximizing conservation of healthy tissue. This technique was developed by Dr. Mohs in the 1930’s. The procedure was originally named “chemosurgery,” since the technique involved the application of a chemical fixative (zinc chloride) to the in-situ tumor. After 24 hours of in-situ fixation, the tumor was excised and microscopically examined. The process was repeated until the tumor was completely removed. Over the following decades, Mohs surgery shifted away from using zinc chloride fixation in favor of processing fresh tissue that was frozen and sectioned in a cryostat microtome. This technique offered several advantages compared to the original chemosurgery technique, including faster processing times (15 to 30 minutes), decreased patient discomfort, and increased tissue conservation. Mohs surgery is appropriate for skin cancers with a high risk of recurrence and when tissue conservation is essential. It is performed by removing a thin margin of tissue circumferentially around and deep to the clinical margins of a skin tumor. The specimen is typically removed with a 45-degree bevel to facilitate tissue processing. It is then rapidly frozen and sectioned in a cryostat microtome, allowing for quick tissue processing (about 15 to 30 minutes). Sectioning the tissue in a horizontal direction allows virtually 100% of the tissue margin (peripheral and deep margins) to be examined under the microscope. The process is repeated until the tumor has negative histologic margins.

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