Mohs micrographic surgery (MMS) is a surgical technique commonly used to treat cutaneous malignancies such as squamous cell carcinoma (SCC) and basal cell carcinoma (BCC). MMS is performed in several stages, progressively removing malignant tissue while preserving healthy tissue and achieving high cure rates. The main advantage of MMS is the ability to assess all margins through the removal of tumor layers, which are processed in frozen sections. This histological assessment of the entire margin is crucial to determine tumor clearance before defect reconstruction, usually occurring in a single surgical session.
MMS is currently the mainstay treatment for non-melanoma skin cancer, including SCC and BCC. MMS has shown benefits in treating these cancers, significantly reducing recurrence rates in both tumors. Uncommon cutaneous malignancies (UCMs) are skin tumors that, although infrequent, are usually associated with poor outcomes and worse prognosis compared to their more common counterparts. MMS has proven useful in treating UCMs, such as dermatofibrosarcoma protuberans. Recently, several studies have highlighted different UCMs treated with MMS, including angiosarcoma, eccrine malignant tumors, Paget disease, and Merkel cell carcinoma (MCC).
Due to their high metastatic potential, MMS's role in treating UCMs has been questioned, especially in angiosarcoma and MCC. Usually, UCMs benefit from treatment with wide local excisions (WLEs). However, MMS has been used alternative option for UCMs over the past decade, supported by several case reports and series demonstrating its beneficial effects on UCM management. In recent years, study groups worldwide have assessed the efficacy, impact on prognosis, and relevance of MMS beyond its common indications. Nonetheless, the value of MMS for some UCMs remains to be fully defined. The following discussion reviews the available evidence on the role of MMS in treating specific UCMs.
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