Mohs micrographic surgery (MMS) has been met with controversy since its inception in the 1930s. Current debate centers on the types of tumors treated with MMS, increasing utilization, third-party payer reimbursement, the Appropriate Use Criteria (AUC), and subspecialty certification.
Controversies in Applications
Controversy surrounding treatment with MMS for certain tumor types is abundant, in large part due to a lack of well-designed studies. Perhaps most notably, the surgical management of melanoma has been hotly contested for decades.1 An increasing number of Mohs surgeons advocate the use of MMS for treatment of melanoma. Advocates reason that tumor margins may be ill-defined, necessitating histologic examination of the margin for tumor clearance. In a study by Zitelli et al,2 5-year survival and metastatic rates for 535 patients with melanomas treated by MMS with frozen sections were the same or better when compared to historical controls treated with conventional wide local excision. Melanoma-associated antigen recognized by T cells (MART-1) immunostaining may offer improved diagnostic accuracy.3 Others believe that staged excision with permanent sections processed vertically, en face, or horizontally (“slow Mohs”) is more accurate and efficacious for the treatment of melanoma.1 Advocates of this approach maintain that when compared to MMS with frozen sections, staged excision with permanent sections enables more accurate interpretation of residual melanoma and atypical junctional melanocytic hyperplasia as well as circumvents difficulty in interpreting freeze artifact.4
Although Merkel cell carcinoma has traditionally been treated with wide local excision, MMS with or without adjuvant radiotherapy has gained traction as a treatment option. Advocates for treatment by MMS hold that Merkel cell carcinoma is a contiguous tumor with a high rate of residual tumor persistence, making histologic margin control an ideal characteristic of treatment. However, in the absence of large randomized controlled studies comparing MMS to wide local excision, controversy surrounds the most appropriate surgical approach.1 In a retrospective study of 86 patients by O’Connor et al,5 MMS was demonstrated to compare favorably to standard surgical excision. Standard surgical excision was associated with a 31.7% (13/41) local persistence rate and 48.8% (20/41) regional metastasis rate compared to 8.3% (1/12) and 33.3% (4/12) for MMS, respectively.5
Controversies in Increasing Utilization
The incidence of skin cancers has increased in recent years. As a result, it is reasonable to expect the rates of MMS to increase. Nonetheless, there is escalating concern among groups of third-party payers, the public, and physicians that MMS is being overused.6 Growth of the body of evidence supporting the appropriateness of MMS remains essential. Such studies continue to support reasons for increased MMS usage, demonstrating the stability of the percentage of skin cancers treated with MMS in the setting of increasing skin cancer incidence, the procedure’s superior efficacy for appropriately chosen cases, its expanding application to melanoma and other tumors, and an emphasis of MMS in residency training programs.6-9