Mohs Micrographic Surgery: Principals and Benefits

At the start of his session, “Understanding Mohs Surgery and Its Indications,” presented at Fall Dermatology Week 2022, Howard Steinman, MD, discussed the principles of Mohs micrographic surgery (MMS) and how it differs from standard excisional techniques.

First, he went over the essential aspects of MMS, starting with the importance of excising specimens so the complete margin can be flattened. Surgeons should then continue transferring the specimen for laboratory analysis while maintaining orientation. Next, a Mohs map of the wound shape should be a reference for nicks or marks, with records of inking and subdivisions. Also, there should be preparations made for pathology slides so these can be examined for areas that might need further surgery. Again, he stressed that the Mohs map should be used to mark these areas. These map findings should finally be used for locating the wound to remove more tissue.

With all these steps, Dr Steinman reviewed the surgeon’s responsibilities that play a major part in the process. He noted that surgeons must perform or supervise the whole procedure, including the excision, tissue transfer, and more. He especially stressed that pathology evaluation and tumor localization are important as well.

“You can’t delegate that to another pathologist or dermatopathologist. For one thing, it’ll make it more difficult for the Mohs surgeons’ brain to correlate where those findings were on the slide back to the map and into the wound, and also you can’t bill from those surgeries,” Dr Steinman elaborated.

Next, Dr Steinman went over the correlations for which thesurgeon is responsible, such as:

• 2-D pathology slides
• 2-D Mohs map
• 3-D wound

Finally, Dr Steinman discussed how MMS differs from a standard excision. For the advantages of MMS, he shared that it evaluates 100% of the surgical margin, has the highest cure rate for almost all skin cancers, and has narrow surgical margins. In comparison, standard excisions only have 1% to 2% of cut margins examined and wider excisions (about ≥4 mm) are often required. He also added that there are many advantages to MMS, including:

• Fast pathology results
• If the patient is insured, it’s often more cost-effective
• The surgeon and pathologist are the same physician

He also added that this is an in-office, local anesthesia procedure. However, he stressed the disadvantages of MMS, such as the extended office time (depending on the patient’s age, comorbidities, and behavioral challenges), the cost if the patient is uninsured, cases that may be better suited for sedation or general anesthesia, and the need for a multispecialty surgical team.

Reference
Steinman H. Understanding Mohs surgery and its indications. Presented at: Dermatology Week 2022; September 14-17, 2022; Virtual.