Due to excellent margin control via immediate microscopic evaluation of surgical margins, MMS is an appropriate treatment choice and indicated for many more uncommon cutaneous malignancies, including sebaceous and mucinous carcinoma, microcystic adnexal carcinoma, Merkel cell carcinoma, leiomyosarcoma, dermatofibrosarcoma protuberans, atypical fibroxanthoma, angiosarcoma, and other more rarely encountered clinical malignancies.2
Tumor size. When considering a referral to MMS for cancer extirpation, the size of the tumor does play a role; however, size depends on the type of tumor as well as the location on the body. In general, most skin cancers of any size on the face, perianal area, genitalia, nipples, hands, feet and ankles, or pretibial surface are appropriate for Mohs surgery. Skin cancers on the trunk and extremities are also appropriate if they are above a certain size specified by the AUC. Tumor type and whether they are recurrences also factor into the equation.
Who will do the procedure?
A recent review showed that PCPs were more likely to refer patients to plastic surgery rather than Mohs surgery for skin cancer removal, especially among younger female patients.4 This is likely because of the perception that plastic surgeons do more complex closures and have more experience removing difficult cancers. Interestingly, this same study showed that Mohs surgeons may actually be doing several-fold more complex closures (flaps and grafts) on the nose and ears than plastic surgeons at similar practice settings.4
Aside from Mohs surgeons doing more closures, perhaps the biggest difference between Mohs surgeons and plastic surgeons is the pathology training of the Mohs surgeon. Mohs surgeons evaluate 100% of the tissue margins at the time of the procedure to both ensure complete tumor removal and to preserve as much tumor-free skin as possible, ultimately resulting in decreased recurrences and smaller scars. In contrast, the plastic surgeon’s rigorous training typically does not include extensive dermatopathology training, particularly the pathology of cutaneous neoplasms. Plastic surgeons will often send pathologic specimens for evaluation, meaning patients have to wait for outside histologic confirmation before their wounds can be closed. Additionally, the histologic evaluation is often not a full-margin assessment, as not all labs are equipped for this technique.
Consider early consultation with a Mohs surgeon for tumor extirpation to keep the defect size as small as possible, as MMS does not require taking margins of healthy surrounding tissue, in contrast to wide local excisions (WLEs; FIGURE 1). A smaller initial incision will result in a smaller scar, which is likely to have better cosmetic outcomes and decreased risk for wound infection.
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