Clinical UM Guideline

This document addresses Mohs micrographic surgery (MMS), an outpatient procedure used in selective situations to treat malignant neoplasms of the skin. MMS consists of a precise tissue-sparing surgical technique to remove and process skin tissue in successive stages.

Note: This document does not address the use of the Munich technique, the Tübingen torte technique or the Tübingen muffin technique. These techniques are similar to MMS in that they use peripheral and deep en face margin assessment (PDEMA). However, unlike MMS, histopathologic evaluation of the tissue is performed by a pathologist rather than by the surgeon at the time of excision. In addition, these techniques are typically performed as staged or standard excisional procedures and are therefore considered forms of excisional surgery rather than MMS.

Note: For a high-level overview of this document, please see “Summary for Members and Families” below.

Medically Necessary:

Mohs micrographic surgery is considered medically necessary for treatment of an individual with a lesion or tumor that meets any of the following:

1. High-Risk Basal Cell Carcinoma defined as having any of the following characteristics:
   1. Any size lesion on head, neck, hands, feet, pretibial or anogenital area; or
   2. Individual is immunosuppressed (such as lymphoma, chronic lymphocytic leukemia, organ transplant recipient, drug-induced, Human Immunodeficiency Virus); or
   3. Lesion in the site of prior radiation therapy; or
   4. Lesions at least 20 mm on trunk or extremities; or
   5. Lesions or tumors having basosquamous, infiltrative, sclerosing/morpheaform, micronodular, or with sarcomatoid differentiation features in any portion of the tumor; or
   6. Perineural involvement; or
   7. Poorly defined clinical borders; or
   8. Recurrent lesion;
      or
2. Low-Risk Cutaneous Squamous Cell Carcinoma defined as having any of the following characteristics:
   1. Histologically positive margins found after standard excision, defined as tumor present at the peripheral or deep margin on permanent section pathology; or
   2. Documented need for complete margin assessment, evidenced by one or more of the following:
      1. Indistinct clinical borders noted on physical examination; or
      2. Tumor extends to the deep margin where further excision risks functional impairment of underlying structures (for example, cartilage, tendon);
         or
   3. Inability to achieve recommended surgical margins with standard excision, demonstrated by any of the following:
      1. Inability to obtain 4 mm or greater clinical margins (or 6 mm or greater when clinically indicated) due to anatomic constraints (for example, nose, eyelid, ear, lip, digits); or
      2. Prior excision attempts resulting in residual tumor despite adherence to guideline-recommended margins;
         or
3. High-Risk Squamous Cell Carcinoma defined as having any of the following characteristics:
   1. Any size lesion on the head, neck, hands, feet, pretibial and anogenital area; or
   2. High risk histologic subtype (adenosquamous or sarcomatoid) in any portion of the tumor; or
   3. Immunosuppression (such as lymphoma, chronic lymphocytic leukemia, organ transplant recipient, drug-induced, Human Immunodeficiency Virus); or
   4. Lesion at least 20 mm but not greater than 40 mm on trunk or extremities; or
   5. Neurologic symptoms; or
   6. Perineural involvement; or
   7. Poorly defined clinical borders; or
   8. Rapidly growing tumor; or
   9. Recurrent lesion; or
   10. Site of prior radiation therapy or chronic inflammation; or
   11. Tumor depth of 2 mm to 6 mm, with no invasion beyond subcutaneous fat;
       or
4. Very-High-Risk Squamous Cell Carcinoma defined as having any of the following characteristics:
   1. Any size lesion greater than 40 mm, in any location; or
   2. High risk histologic subtype (adenosquamous or sarcomatoid) in any portion of the tumor; or
   3. Lymphatic or vascular involvement; or
   4. Poorly differentiated tumor cells; or
   5. Tumor cells within the nerve sheath of a nerve with one of the following characteristics:
      1. The nerve lies deeper than the dermis; or
      2. The perineural tumor measuring greater than or equal to 0.1 mm;
         or
   6. Tumor depth greater than 6 mm or invasion beyond subcutaneous fat;
      or
5. Melanoma defined as having any of the following characteristics:
   1. Acral lentiginous subtypes (located on soles, palms, sub-ungual sites); or
   2. Melanoma in Situ (Stage 0) and the inability to achieve recommended surgical margins with standard excision, as demonstrated by any of the following:
      1. Inability to obtain 5 mm or greater clinical margins (or 10 - 20 mm or greater when clinically indicated) due to anatomic constraints (for example, nose, eyelid, ear, lip, digits); or
      2. Prior excision attempts resulting in residual tumor despite adherence to guideline-recommended margins;
         or
   3. Poorly defined Melanoma in Situ (Stage 0); or
   4. Lentigo Maligna in an area with high cumulative sun damage; or
   5. Minimally invasive (T1a) melanomas in anatomically constrained areas (for example face, ears, acral sites);
      or
6. The lesion to be treated is known to be any of the following:
   1. Adenocystic carcinoma; or
   2. Adnexal carcinoma; or
   3. Apocrine/eccrine carcinoma; or
   4. Atypical fibroxanthoma; or
   5. Dermatofibrosarcoma protuberans; or
   6. Extramammary Paget disease; or
   7. Leiomyosarcoma; or
   8. Malignant fibrous histiocytoma/undifferentiated pleomorphic sarcoma; or
   9. Merkel cell carcinoma; or
   10. Microcystic adnexal carcinoma; or
   11. Mucinous carcinoma; or
   12. Sebaceous carcinoma.

Not Medically Necessary:

Mohs micrographic surgery is considered not medically necessary when the criteria above have not been met.

This document describes clinical studies and expert recommendations and explains when Mohs micrographic surgery (MMS) is appropriate. The following summary does not replace the medical necessity criteria or other information in this document. The summary may not contain all of the relevant criteria or information. This summary is not medical advice. Please check with your healthcare provider for any advice about your health.

Key Information

MMS is a skin surgery used to treat some types of skin cancer. The goal of MMS is to remove the cancer while saving as much healthy skin as possible. A doctor removes thin layers of skin, one layer at a time, and looks at each layer under a microscope to see if cancer remains. This process is repeated until no cancer is found. MMS can lower the chance that the cancer will come back. It is often used for skin cancers on sensitive areas like the face or hands, where keeping as much healthy skin as possible is important. People usually stay awake during MMS and go home the same day. The procedure may cause side effects such as pain, bleeding, swelling, infection, or numbness. In some cases, additional surgery may be needed to repair the area.

What the Studies Show

MMS is most often used to treat common types of skin cancer such as basal cell carcinoma (BCC), squamous cell carcinoma (SCC), and melanoma in situ (melanoma that has not spread), especially when the tumor is in a high-risk location (for example, hands, neck, head or feet), is large, has grown back after treatment, or has other aggressive features. MMS is also used to treat less common skin cancers. Studies have found that MMS lowers the chance that the cancer will come back, especially for tumors on the face or other high-risk areas. One long-term study found that BCC on the face came back less often after MMS than after regular surgery. For SCC, MMS has also shown high cure rates. For melanoma in situ, including lentigo maligna (a very early form of melanoma limited to the top layer of the skin), MMS may reduce recurrence, especially for lesions on the face. However, better studies are needed to know how well MMS improves health compared to other treatments for melanoma. MMS may also help in treating rare skin cancers like Merkel cell carcinoma (MCC) and dermatofibrosarcoma protuberans (DFSP). In these cases, studies suggest that MMS may reduce the chance of recurrence, but more high-quality research is needed. Overall, MMS has been found to be as effective, or sometimes more effective, than other treatments for certain types of skin cancer.

When is Mohs Micrographic Surgery Clinically Appropriate?

Mohs micrographic surgery may be appropriate in these situations:

• High-risk basal cell carcinoma, if:
  • Tumors at least 20 mm on the trunk or limbs; or
  • Tumors of any size on the head, neck, hands, feet, pretibial, or genital areas; or
  • Tumors with unclear borders, those that returned after treatment, or occurred in someone with a weak immune system; or
  • Tumors in areas previously treated with radiation; or
  • Tumors showing aggressive growth patterns or nerve involvement.
• Low-risk squamous cell carcinoma, if:
  • There are cancer cells at the edge of the tissue after regular surgery; or
  • There is a need to fully check the edges due to unclear borders or tumor depth near important structures; or
  • It is not possible to remove enough surrounding tissue with regular surgery due to body location or prior unsuccessful surgeries.
• High-risk squamous cell carcinoma, if:
  • Lesion is 20-40 mm on trunk or limbs, or
  • Lesion of any size on head, neck, hands, feet, pretibial, or anogenital, or
  • Borders are hard to define, or
  • Cancer has come back, or
  • Individual has a weak immune system, or
  • Area was treated with radiation or has chronic inflammation, or
  • Tumor is growing quickly, or
  • Individual has nerve-related symptoms, or
  • Certain subtypes are found under a microscope, or
  • Tumor is 2-6 mm deep and does not go beyond fat, or
  • Cancer involves nerves.
• Very-high-risk squamous cell carcinoma, if:
  • Lesion is over 40 mm (anywhere), or
  • Tumor is poorly differentiated, or
  • Certain subtypes are found under a microscope, or
  • Tumor is deeper than 6 mm or goes beyond fat, or
  • Perineural tumor measuring greater than or equal to 0.1 mm, or
  • Cancer affects lymph or blood vessels.
• Melanoma in situ, if:
  • It is lentigo maligna melanoma with limited invasion in a hard-to-treat area like the face, ears, or acral sites, or
  • The tumor is hard to define, especially if it is lentigo maligna or acral lentiginous type.
• Other rare skin cancers, if the lesion is:
  • Adenocystic carcinoma, or
  • Adnexal carcinoma, or
  • Apocrine/eccrine carcinoma, or
  • Atypical fibroxanthoma, or
  • Dermatofibrosarcoma protuberans, or
  • Extramammary Paget disease, or
  • Leiomyosarcoma, or
  • Malignant fibrous histiocytoma/undifferentiated pleomorphic sarcoma, or
  • Merkel cell carcinoma, or
  • Microcystic adnexal carcinoma, or
  • Mucinous carcinoma, or
  • Sebaceous carcinoma.

When is this not Clinically Appropriate?

MMS is not appropriate when any of the above conditions are not met. MMS is a specialized procedure meant for certain cancers or situations. Studies show that MMS is most useful for cancers with specific risk factors or locations. Better studies are needed to know if MMS helps for other types of skin cancer or for cancers in low-risk areas.

(Return to Description)

The following codes for treatments and procedures applicable to this guideline are included below for informational purposes. Inclusion or exclusion of a procedure, diagnosis or device code(s) does not constitute or imply member coverage or provider reimbursement policy. Please refer to the member's contract benefits in effect at the time of service to determine coverage or non-coverage of these services as it applies to an individual member.

When services may be Medically Necessary when criteria are met:

When services are Not Medically Necessary:
For the procedure and diagnosis codes listed above when criteria are not met or for all other diagnoses not listed; or when the code describes a procedure or situation designated in the Clinical Indications section as not medically necessary.

Summary

This guideline outlines when Mohs micrographic surgery (MMS) is appropriate for treating skin cancers, focusing on lesions in high-risk anatomic sites, tumors with aggressive or recurrent features, and certain less common cutaneous malignancies. It aligns with recommendations from national organizations, including National Comprehensive Cancer Network^® (NCCN) guidance supporting MMS or other exhaustive margin-assessment techniques for high-risk basal cell carcinoma (BCC), squamous cell carcinoma (SCC), melanoma in situ, and select rare tumors. Evidence summarized in the policy reflects consistently low recurrence rates across studies, with MMS offering particular value where tissue preservation and complete margin control are essential.

Discussion

According to the American Cancer Society (ACS, 2022), skin cancer is the most common cancer diagnosis in the U.S. The majority of skin cancers are BCC or SCC. Approximately 5.4 million BCC and SCC skin cancers are diagnosed each year in the U.S., of which about 80% are BCC. The relative incidence of BCC and SCC may differ in other countries; for example, in Israel, the incidence of BCC decreased between 2006 and 2011, whereas the incidence of SCC increased during that time period (Sella, 2015). Mortality from BCC and SCC is uncommon and occurs primarily in individuals who are immunosuppressed or who have had organ transplants. Melanoma, on the other hand, accounts for about 1% of skin cancers, but is associated with most of the skin cancer deaths. The ACS estimates that, in 2025, about 104,960 new cases of melanoma were diagnosed in the U.S. and about 8430 individuals will die due to melanoma.

Less common types of skin cancer include Merkel cell carcinoma (MCC) and dermatofibrosarcoma protuberans (DFSP). MCC is an aggressive and potentially fatal form of skin cancer, with approximately 3000 new cases diagnosed annually according to the ACS (2025). DFSP is relatively uncommon and slow growing but is locally aggressive with a high recurrence rate.

Treatments for skin cancer include: 1) topical therapies, 2) locally destructive techniques such as cryotherapy, 3) curettage and electrodesiccation, 4) radiotherapy, 5) surgical excision with margin evaluation, and 6) MMS. Surgical excision, with or without lymph node management and/or adjuvant therapy, is standard treatment for melanoma whereas a wider variety of treatments can be used with BCC and SCC, depending on the clinical situation and the individual’s preference (National Cancer Institute, 2018).

MMS is a technique for the removal of complex or ill-defined skin cancer with histologic examination of 100% of the surgical margins. This is in contrast to surgical excision in which surgical margins are mainly examined in random vertical sections. MMS is a combination of surgical excision and surgical pathology that requires a single physician to act in two integrated but separate and distinct capacities: surgeon and pathologist. The first stage of the procedure describes the histology of the specimens taken from the site, including the depth of invasion, pathological pattern, cell morphology, and, if present, perineural invasion or presence of scar tissue. For subsequent stages, the surgeon may note that the pattern and morphology of the tumor, if still seen, is as described for the first stage, or, if differences are found, note the changes. If residual tumor remains, additional stages of surgical excision are needed to remove the “roots” of the tumor. After the tumor is removed, reconstruction may be needed to repair the surgical defect. The procedure is generally performed on an outpatient basis under local anesthesia.

An advantage of the MMS procedure is that it allows the greatest amount of surrounding healthy tissue to remain intact, potentially reducing the size of the final surgical defect and resulting scar. Thus, it is of particular interest for treating sites such as the face, nose, scalp, neck, hands, and genital area due to its capacity to minimize dysfunction and disfigurement. In addition, the methodical manner in which all lateral and deep tissue margins are examined enables the surgeon to detect and remove any of the remaining skin cancer that may be present, which may reduce the likelihood of recurrence.

Risks associated with MMS can include pain or tenderness, bleeding, redness, swelling, and drainage at the affected site. As with all surgical procedures, there is a risk for infection, although this rarely occurs. Some adverse effects that may occur include numbness or weakness surrounding the surgical area, which can be temporary or permanent, scarring, and itching or acute pain at the surgical site.

In 2012, the American Academy of Dermatology (AAD)/American College of Mohs Surgery (ACMS)/American Society for Dermatologic Surgery Association (ASDAS)/ and the American Society of Mohs Surgery (ASMS) jointly published appropriate use criteria for MMS. The organizations developed 270 scenarios, each of which were rated by a panel of experts as appropriate, uncertain, or inappropriate for Mohs surgery. Consensus was reached among at least 12 of 17 panel members on all scenarios. A total of 200 (75%) of scenarios were considered appropriate, 24 (9%) uncertain and 45 (17%) inappropriate. Regarding melanoma in situ and lentigo maligna, treatment with MMS was considered appropriate if lesions occurred on the forehead, scalp, neck, jawline, pretibial surface, central face, eyelids, genitalia, hands, feet, nail units, ankles and nipples/areola . In addition, MMS was considered appropriate for primary lesions on the trunk and extremities, but not for locally recurrent lesions.

Basal cell carcinoma and squamous cell carcinoma

The NCCN BCC guideline (V.1. 2026) lists MMS as an option for primary local treatment of high-risk basal cell skin cancer and local treatment of low-risk basal cell skin cancer with positive margins after standard excision. The guideline also states that MMS is a specific type of surgery in the general category of peripheral and deep en face margin assessment (PDEMA) with permanent section analysis or intraoperative frozen section analysis. Other forms include the Munich technique, the Tübingen torte technique and the Tübingen muffin technique, which are done in Europe, but are not common in the U.S. As part of the rationale for the guideline, the authors cited a randomized controlled trial (RCT) by van Loo and colleagues, described below, and two meta-analyses from the 1980s that showed a 5-year recurrence rate after MMS of 1.0% for primary BCC and 5.6% for recurrent BCC (Schmults, 2023).

High-risk BCC was defined as:

• Trunk and extremities: ≥2 cm
• Head, neck, hands, feet, pretibial and anogenital area: Any size

The guideline listed the following as “other” high-risk features of BCC:

• Poorly defined clinical borders
• Recurrent lesion
• Immunosuppressed
• Site of prior radiation treatment
• Pathology: aggressive growth pattern, defined as having “ basosquamous, infiltrative, sclerosing/morpheaform, micronodular and BCC with sarcomatoid differentiation features in any portion of the tumor.”
• Perineural involvement

In 2022, Lacerda and colleagues published a systematic review of studies on BCC recurrence rates after various types of micrographic surgery. They identified 18 studies; of these, 6 used the Mohs technique, 8 used the Tübingen technique, 3 used the Munich technique and 1 used the Muffin technique. The overall BCC relapse rate was 2% (95% confidence interval [CI], 1 to 3%). The relapse rate by technique was 3% for Mohs (95% confidence interval [CI], 1 to 5%), 3% for the Munich technique (95% CI, 2 to 5%), 1% for the Tübingen technique (95% CI, 1-2%) and the single study on the Muffin technique had a 0% recurrence rate (95% CI, 0 to 6%). The authors concluded that relapse rates appear to be similar among the techniques but noted a lack of head-to-head trials.

The NCCN SCC guideline (V.1, 2026) recommends Mohs as an option for high-risk or very high-risk SCC and that PDEMA with permanent section analysis or intraoperative frozen section analysis is an alternative to Mohs. ‘Very high-risk’ was defined as lesions greater than 4 cm in any location. MMS was recommended for low risk cutaneous SCC (cSCC) with positive margins on standard excision and as an option for local, low-risk cSCC as primary treatment when margin control and tissue preservation are important or when achieving generous margins with standard excision is challenging. MMS was also recommended as primary treatment for high-risk or very-high-risk cSCC where surgery or radiation therapy has a high likelihood of cure. Evidence cited in the guideline includes a 1992 meta-analysis which found local recurrence rates of 3.1% for primary cSCC and 10% for recurrent cSCC, after up to 5 years of follow-up (Schmults, 2021).

High-risk SCC was defined as:

• Trunk and extremities 2 cm - <4 cm
• Head, neck, hands, feet, pretibial, and anogenital area (any size)

The list of “other risk-factors” for high-risk SCC were as follows:

• Poorly defined clinical borders
• Recurrent lesion
• Immunosuppressed
• Site of prior radiation treatment or chronic inflammation
• Rapidly growing tumor
• Neurologic symptoms
  ​​​​​​​Pathology:
• Histologic subtype (adenosquamous or sarcomatoid subtypes in any portion of the tumor)
• Depth: 2-6 mm depth and no invasion beyond subcutaneous fat
• Perineural involvement, lymphatic or vascular involvement

Very-high-risk SCC has a size of > 4 cm in any location. The “other risk factors” include the following:
Pathology:

• Poorly differentiated histology
• Adenosquamous or sarcomatoid histologic subtypes in any portion of the tumor
• Depth > 6 mm or invasion beyond subcutaneous fat
• Perineural involvement: Tumor cells within the nerve sheath of a nerve lying deeper than the dermis or measuring > 0.1 mm
• Lymphatic or vascular involvement

A systematic review by Yadlapati (2025) compares MMS with wide local excision (WLE), including vulvectomy, for the treatment of anogenital SCC. There were 70 studies encompassing 1271 individuals that were analyzed (n=911 treated with WLE and n=360 with MMS). MMS was associated with a significantly lower local recurrence rate than WLE (5.0% vs. 17.7%; p<0.0001), while regional and distant recurrence rates were similar between approaches. Subgroup analyses for vulvar and penile SCC demonstrated consistent reductions in local recurrence with MMS compared to WLE, supporting its margin-controlled, tissue-sparing advantage in anatomically and functionally sensitive regions. The subgroup of penile tumors with 503 individuals included, had 260 treated with MMS and 243 treated with WLE. MMS offers a significant advantage as it provides 100% histologic margin assessment while WLE provides only 1%. Although those individuals where MMS was used tended to have smaller tumors and shorter follow-up, the overall findings suggest that MMS provides superior local disease control without increasing metastatic risk, making it a reasonable and often preferable surgical option for selected cases of anogenital SCC. Limitations in the study include tumor characteristics between the groups, heterogeneity among studies included, and varying follow up lengths. The findings, however, support the AAD/ACMS/ASDAS/ASMS 2012 appropriate use criteria for anogenital SCC using MMS.

Stevens (2023) used a large retrospective cohort from two major academic centers analyzing 10,196 cSCC tumors from 8727 individuals diagnosed between 1996 and 2019. Tumors were classified into low-, high-, and very high-risk groups per the 2022 NCCN guidelines, which newly introduced a “very high-risk” category and recommended MMS or PDEMA for high-risk disease. High- and very high-risk tumors had substantially higher rates of poor outcomes, including local recurrence, modal metastasis, distant metastasis and disease-specific death. Very high-risk tumors showed dramatically higher 5-year cumulative incidence of all adverse outcomes compared with both high- and low-risk groups. Tumors treated with Mohs or PDEMA had significantly lower risks of local recurrence, distant metastasis, and disease-specific death compared with those treated using WLE, even after adjusting for risk group and individual factors. The study demonstrates that the 2022 NCCN cSCC risk stratification system accurately predicts prognosis and that Mohs or PDEMA improves outcomes for higher-risk tumors. These results support the NCCN guideline changes and suggest that individuals with high- and very high-risk cSCC may have better oncologic outcomes from more aggressive surgical management and potentially closer surveillance.

In 2018, the AAD published guidelines on the management of BCC (Kim, 2018a) and on management of cutaneous SCC (Kim, 2018b). MMS was recommended for high-risk BCC and high-risk cutaneous SCC. The AAD cited the NCCN’s definitions of high-risk for these conditions.

Van Loo and colleagues (2014) published an RCT with long-term follow-up comparing MMS with surgical excision for individuals with BCC of the face. The study included 408 high-risk facial primary BCCs and 204 facial recurrent BCCs. Median follow-up was 79.2 months for primary BCC and 85.0 months for recurrent BCC. Disease recurrence, the primary study outcome, was significantly lower after MMS compared to surgical excision in individuals with recurrent BCC, but not for those with primary BCC. Among individuals with recurrent BCC, the 10-year cumulative probability of recurrence was 3.9% (95% CI, 1.2% to 11.7%) after MMS and 13.5% (95% CI, 7.6% to 23.2%) after surgical excision (p=0.023). In the primary BCC group, the 10-year cumulative probability of recurrence was 4.4% (95% CI, 1.9% to 9.8%) after MMS and 12.2% (95% CI, 7.3% to 19.8%) after surgical excision (p=0.10).

A Cochrane systematic review on interventions for BCC (Thomson, 2020) identified a total of 52 RCTs, only 1 of which compared MMS and surgical excision. The authors commented that there may be slightly fewer recurrences with MMS than surgical excision but that the certainty of evidence was low. Other Cochrane reviews on cutaneous Bowen’s disease (Bath-Hextall, 2016) and periocular BCC (Narayanan, 2014) searched for but did not identify any RCTs evaluating MMS.

Several systematic reviews that included observational studies have been published. In 2013, Lansbury and colleagues examined interventions for non-metastatic SCC. The authors identified 16 uncontrolled studies reporting outcomes after MMS. A pooled analysis of data on cure rates at 5 years in 2133 SCCs treated with MMS was 97.4% (95% CI, 96.2% to 98.3%). Pooled 5-year cure rates by lesion location were trunk and extremities (95.7%), ear (96.6%), face scalp and neck (97.8%), eyelid (98.5%) and nose (98.8%). Ten studies reported local recurrence rates. A pooled analysis of these studies found an average local recurrence rate of 3% after MMS (95% CI, 2.2% to 3.9%).

A systematic review of observational studies on periocular BCC was published by Phan and colleagues (2020). The authors identified 35 studies reporting recurrence rates after one or more types of surgical excision. Of these, 10 studies evaluated MMS, 12 studies evaluated frozen section evaluation (FSE) and 14 studies evaluated WLE. The pooled recurrence rate was 2.9% (95% CI, 1.9 to 4.4%) after MMS, 1.9% (95% CI, 1.9-2.4%) after FSE and 5.9% (95% CI, 3.9-8.9%) after WLE. The recurrence rate was significantly higher after WLE than either MMS or FSE (p<0.001) but not significantly different between MMS and FSE (p=0.65). A limitation of this analysis is that individuals were not randomized to treatment group and most studies were not head-to-head comparisons, so treatment groups may have differed in ways that affected outcomes.

Lee and colleagues (2019) published a systematic review of studies comparing outcomes after surgical excision, MMS, external-beam radiotherapy (EBRT) or brachytherapy (BT) in individuals with indolent BCC or SCC. The authors identified 58 eligible studies (single-arm or comparative study design with at least 10 participants and 10 or more months of follow-up) with a total of 21,371 individuals. For local recurrence rates at 5 years, MMS studies showed a recurrence rate of 2.1%, comparable to that of surgical excision (1.8%) and BT (2.5%). The 5-year local recurrence rate of EBRT was 6.7%, significantly higher than rates for other treatment modalities.

Melanoma in situ (including lentigo maligna)

Lentigo maligna is a subtype of melanoma in situ, representing melanoma confined to the epidermis that arises most commonly on chronically sun-exposed skin, such as the face and scalp. While all lentigo maligna lesions meet the definition of melanoma in situ, not all melanoma in situ represents lentigo maligna, as other subtypes may occur on less sun-exposed areas. Lentigo maligna is characterized by lentiginous growth with extension along adnexal structures, which may result in ill-defined clinical margins and can complicate complete surgical excision.

A Cochrane systematic review on interventions for melanoma in situ (Tzellos 2016) did not identify any RCTs evaluating MMS.

A 2019 study by Phan and Loya conducted a retrospective analysis of cases of melanoma in situ from the Surveillance, Epidemiology and End Results (SEER) cancer registry. The study identified 24,515 individuals treated with WLE and 4122 individuals treated with MMS. After adjusting for confounding factors, there were no significant differences between groups in disease-specific survival (Hazard Ratio [HR], 0.98; 95% CI, 0.60-1.45; p=0.74) or overall survival (OS) (HR, 1.01; 95% CI, 0.90-1.23; p=0.92). The study did not report recurrence rates.

A 2017 study by Nosrati and colleagues evaluated outcomes in individuals with melanoma in situ who were treated with MMS (n=277) or WLE (n=385). The study was retrospective and non-randomized. Median follow-up was 8.6 years (range, 0.2 to 37 years). MMS was used more frequently in lesions on the face, scalp, and neck whereas WLE was more common in lesions on the trunk and extremities. The rate of tumor recurrence was 1.8% after MMS and 5.7% after WLE (p=0.07). The calculated 15-year recurrence rate was 5.0% (95% CI, 1.4% to 17.3%) in the MMS group and 7.3% (95% CI, 4.8% to 11.0%) in the WLE group. There was not a statistically significant difference in the OS rate for individuals treated with WLE or MMS. A 2015 study by Hou and colleagues also evaluated outcomes after MMS (n=154) or wide excision (n=269) for lentigo maligna. Recurrence rates after 5 years were 1.9% in the MMS group and 5.9% in the wide excision group. Treatments were not compared due to the retrospective nature of the study design.

A 2021 systematic review by Sharma and colleagues identified 27 studies examining the effectiveness of MMS for treating lentigo maligna. All of the studies were observational; no RCTs were identified. Sample size in individual studies ranged from 12 to 1506 individuals. When reported recurrence rates were pooled, recurrence was observed in 41 cases out of a total of 3033 excisions (1.35%). Mean follow-up in the studies ranged from 3 months to 5 years.

Less common cutaneous skin cancers

The NCCN also addresses less common skin cancers.

The Merkel Cell Carcinoma guideline (V.2. 2026) states the following:

It is recommended, regardless of the surgical approach, that every effort be made to coordinate surgical management such that SLNB [sentinel lymph node biopsy] is performed prior to or at the time of definitive excision. Excision options include:

• If adjuvant RT [radiotherapy] is planned, narrow excision margins are likely sufficient.
• If adjuvant RT may not be indicated, perform wide excision with 1- to 2-cm margins to the investing fascia layer of muscle or pericranium when clinically feasible and consistent with reconstruction and radiation goals…
• Techniques for more exhaustive histologic margin assessment may be considered (Mohs or other forms of PDEMA), provided they do not interfere with SLNB. If SLNB is not performed concurrently, it is recommended that SLNB is performed prior to definitive excision.

The Dermatofibroscarcoma Protuberans (V.2, 2026) NCCN guideline states:

Because of its proclivity for irregular and frequently deep subclinical extensions, every effort should be made to remove this tumor in its entirety at the time of initial therapy. Excision with Mohs micrographic surgery (Mohs) or other forms of peripheral and deep en face margin assessment (PDEMA) is recommended over WLE.

Several systematic reviews of the literature on some of these less common cancers have been published. The published literature on these cancers is limited by the small number of comparative studies, especially RCTs. In 2022, St. Martin and colleagues published a systematic review and meta-analysis of comparative and non-comparative studies on individuals with DFSP who were treated with MMS and/or WLE. Included studies had at least 5 participants and reported recurrence rates. A total of 88 studies met eligibility criteria, 12 comparative studies and 76 single-arm studies. A pooled analysis of the 76 single-arm studies found a significantly lower rate of local recurrence after MMS (1.5%) than after WLE (9.4%, p<0.001). However, a pooled analysis of data from the 12 comparative studies found a non-significant odds ratio (OR) of 1.55 (95% CI, 0.71 to 3.38, p=0.27) for local recurrence after treatment with WLE compared to MMS.

Remiszewski (2025) noted the primary treatment for DFSP is complete surgical removal, as local recurrence can result from incomplete excision. Surgical margin width is a critical determinant of outcomes. Narrow margins (< 3 cm) are associated with significantly higher rates of residual tumor and recurrence, while wider margins reduce these risks but increase surgical morbidity. The authors cited a meta-analysis involving eight trials that demonstrated that margins ≥ 3 cm significantly reduced local recurrence compared to margins < 3 cm margin (recurrence rate relative risk [RR], 0.17, 95% CI, 0.09-0.31; and positive surgical margin rate RR, 0.09, 95% CI, 0.02-0.46). MMS has become the preferred approach for DFSP because it allows near-complete microscopic evaluation of tumor margins while preserving healthy tissue. Compared with traditional WLE, MMS achieves much lower recurrence rates, even with smaller lateral margins, making it particularly valuable in anatomically sensitive areas.

A systematic, comprehensive review by Sharifi (2025) evaluated the use of MMS for genital skin cancers, including extramammary Paget’s disease (EMPD), DFSP, SCC, and BCC. An analysis of 24 studies encompassing 166 cases demonstrated an overall 95% cure rate with MMS and consistently low recurrence across tumor types (EMPD 3%, DFSP 0%, SCC 12%, BCC 2%). Compared with traditional approaches such as WLE or vulvectomy, MMS offers superior margin control while preserving critical genital structures, thereby reducing functional and cosmetic morbidity. MMS was effective both as a primary treatment and as salvage therapy after prior surgical failure. Despite limitations related to small study sizes and heterogeneous follow-up, the findings support MMS as a highly effective, tissue-sparing option for selected genital cancers and align with current NCCN guideline recommendations.

Carrasquillo and colleagues (2022) reviewed data on MMS and WLE in individuals with MCC. The authors identified 31 studies using WLE, 3 studies using MMS, and 6 studies that included some cases treated with each approach. A total of 1996 individuals were treated with WLE. Outcomes were not reported for all individuals. Studies reported 194 local recurrences in 1967 individuals (9.9%) and regional recurrence in 257 of 1332 (19.3%) individuals. For MMS, 10 of 112 individuals (8.9%) had local recurrences and 18 of 103 (17.5%) had regional recurrences. Less data was available for other outcomes, including distant recurrence and mortality.

Atypical fibroxanthoma is a rare, typically superficial skin cancer that most often arises on chronically sun-exposed areas, particularly the head and neck of older adults. It is characterized by pleomorphic spindle and epithelioid cells confined largely to the dermis and, despite often aggressive microscopic features, generally demonstrates low metastatic potential when adequately excised. A systematic review and meta-analysis on atypical fibroxanthoma was published in 2018 by Tolkachjov. The authors identified 23 studies evaluating individuals with a diagnosis of atypical fibroxanthoma who were treated with MMS or WLE. Two of the studies were non-randomized comparative studies and the other 21 studies were noncomparative. There were 175 individuals treated with MMS; the local recurrence rate was 2% (95% CI, 0% to 4.1%) and 8.7% (95% CI, 55 to 12.3%). There were a total of 22 metastases, 1.9% in the MMS group and 1.0% in the WLE group.

Melanoma (other than melanoma in situ)

The NCCN Cutaneous Melanoma guideline (V.2, 2025) states:

Mohs micrographic surgery (MMS) is not recommended for primary treatment of invasive cutaneous melanoma when standard clinical margins can be obtained.

• MMS may be considered selectively for minimally invasive (T1a) melanomas in anatomically constrained areas (ie face, ears, acral sites), along with other surgical methods that provide comprehensive histologic assessment, such as staged excision with permanent sections for dermatopathology review.
• If MMS is performed, the central debulking specimen should be analyzed histologically via permanent sections (preferred) or frozen sections with immunostaining to provide complete staging information.

In 2019, Cheraghlou and colleagues published an analysis of data from the National Cancer Database on outcomes after treatment with wide margin excision (WME) or MMS. The analysis included 70,319 individuals, 67,085 treated with WME and 3234 treated with MMS. In univariate Kaplan-Meier analysis, rates of OS were similar in individuals treated with MMS or WME (HR, 1.01; 95% CI, 0.90-1.14). In a multivariate regression model using propensity-score matching, MMS was associated with a statistically significant improvement in OS compared with WME (HR, 0.86, 95% CI, 0.76 to 0.97). A subgroup analysis by lesion location did not find a statistically significant difference in OS in the two groups for primary lesions that were not on the head or neck (HR, 0.92; 95% CI, 0.77-1.11). An analysis limited to primary lesions located on the head and neck found significantly improved overall survival in individuals treated with MMS compared with WME (HR, 0.81; 95% CI, 0.69-0.96). Despite the large number of individuals included in the overall study, after propensity score matching, there were only 2589 individuals treated with MMS, 758 with lesions on the head or neck.

A 2021 analysis of the National Cancer Database by Demer and colleagues did not find a statistically significant difference in 5-year OS rates between individuals with trunk and extremity melanoma who were treated with WLE or with MMS. Out of 188,862 individuals in the analysis, only 2.3% (4413) were treated with MMS. In multivariate analysis, factors associated with increased risk of 5-year OS included increasing age (HR, 1.043, 95% CI, 1.042-1.044), tumor ulceration (HR, 2.175; 95% CI, 2.114-2.238), superficial spreading tumor (HR, 0.739, 95% CI, 0.710-0.769) and lentigo maligna melanoma (2.9% of cases) (HR, 0.743, 95% CI, 0.686-0.805).

A systematic review (Williams, 2024) evaluated the literature on MMS for invasive melanoma. A total of 35 studies met their eligibility criteria. None of the studies were RCTs and 16 were observational studies comparing outcomes after MMS and WLE. Due to heterogeneity among studies, only a limited number of quantitative meta-analyses were performed. A pooled analysis of data from 4 studies reporting multivariate analysis of all-cause mortality found no significant difference in this outcome in those treated with MMS or WLE (HR, 0.97, 95% CI, 0.91 to 1.04). Another pooled analysis of 6 studies reporting rates of local recurrence did not find a statistically significant difference in Mohs and WLE-treated individuals (RR, 0.46, 95% C, 0.14 to 1.51).

Basal cell carcinoma: A type of cutaneous skin cancer that begins in the basal cells (the innermost layer of the epidermis).

Cutaneous: Of or related to the skin.

Lentigo maligna: A type of melanoma in situ. Slow-growing lesion that remains close to the skin surface for a long time. It generally occurs in chronically sun-exposed skin. When it becomes invasive, it is known as lentigo maligna melanoma.

Melanoma in situ: Also known as Stage 0 melanoma. The tumor is confined to the epidermis.

Mohs micrographic surgery: A staged surgical excision and margin-assessment technique used in the treatment of selected cutaneous malignancies, in which the tumor is removed in sequential layers and each layer is processed and examined microscopically with complete circumferential evaluation of peripheral and deep margins. Tissue processing and histologic interpretation are performed during the procedure, allowing targeted removal of residual tumor while preserving uninvolved tissue. Mohs micrographic surgery represents a form of peripheral and deep en face margin assessment (PDEMA).

Munich Technique: The Munich method is a variant of Mohs surgery that achieves complete margin control without saucerization. Instead of flattening peripheral and deep margins into a single plane and cutting beveled sections, the tumor is excised with narrow margins (1-3 mm) and processed in its native shape. The specimen is oriented, inked, and mapped, then serial horizontal frozen sections are cut from the deep margin upward to the skin surface. This allows simultaneous evaluation of the tumor and both peripheral and deep margins. If residual tumor is identified at any margin, targeted re-excision is performed and repeated until clearance is achieved, followed by healing by second intention or reconstruction.

Peripheral and Deep En Face Margin Assessment (PDEMA): A surgical margin-assessment approach used in the treatment of selected cutaneous malignancies in which the entire peripheral and deep surgical margins are examined microscopically using en face sectioning. PDEMA allows complete circumferential evaluation of tumor margins, in contrast to traditional vertical bread-loaf sectioning, and may be performed using intraoperative or delayed histologic processing. Techniques that employ PDEMA include Mohs micrographic surgery and other staged or oriented excision methods.

Squamous cell carcinoma: A type of skin cancer that develops in squamous cells in the epidermis, the skin’s outermost layer.

Tübingen Muffin Technique: A single-stage surgical excision technique used in the treatment of melanoma in situ, in which the entire lesion is removed in one specimen and processed in a manner that permits comprehensive microscopic evaluation of both peripheral and deep margins by a dedicated pathologist. The specimen is oriented to allow circumferential assessment, frequently with the use of immunohistochemical staining, to confirm complete excision.

Tübingen Torte Technique: A staged surgical margin-assessment technique used in the treatment of melanoma in situ, in which the peripheral margins surrounding a clinically visible lesion are excised and examined microscopically as a separate specimen by a dedicated pathologist, while the central lesion is temporarily left in place. Following confirmation of negative peripheral margins, the central lesion is subsequently removed. This technique is designed to allow complete circumferential margin evaluation, often with the use of immunohistochemical staining.

Peer Reviewed Publications:

1. Carrasquillo OY, Cancel-Artau KJ, Ramos-Rodriguez AJ, et al. Mohs micrographic surgery versus wide local excision in the treatment of merkel cell carcinoma: a systematic review. Dermatol Surg. 2022; 48(2):176-180.
2. Cheraghlou S, Christensen SR, Agogo GO, et al. Comparison of survival after Mohs micrographic surgery vs wide margin excision for early-stage invasive melanoma. JAMA Dermatol. 2019; 155(11):1252-1259.
3. Demer AM, Hanson JL, Maher IA, et al. Association of Mohs micrographic surgery vs wide local excision with overall survival outcomes for patients with melanoma of the trunk and extremities. JAMA Dermatol. 2021; 157(1):84-89.
4. Hou JL, Reed KB, Knudson RM, et al. Five-year outcomes of wide excision and Mohs micrographic surgery for primary lentigo maligna in an academic practice cohort. Dermatol Surg. 2015; 41(2):211-218.
5. Lacerda PN, Lange EP, Luna NM, et al. Recurrence rate of basal cell carcinoma among different micrographic surgery techniques: systematic review with meta-analysis. J Eur Acad Dermatol Venereol. 2022; 36(8):1178-1190.
6. Lansbury L, Bath-Hextall F, Perkins W, et al. Interventions for non-metastatic squamous cell carcinoma of the skin: systematic review and pooled analysis of observational studies. BMJ. 2013; 347:1-46.
7. Lee CT, Lehrer EJ, Aphale A, et al. Surgical excision, Mohs micrographic surgery, external-beam radiotherapy, or brachytherapy for indolent skin cancer: an international meta-analysis of 58 studies with 21,000 patients. Cancer. 2019; 125(20):3582-3594.
8. Martin ECS, Vyas KS, Batbold S, et al. Dermatofibrosarcoma protuberans recurrence after wide local excision versus Mohs micrographic surgery: a systematic review and meta-analysis. Dermatol Surg. 2022; 48(5):479-485.
9. Nosrati A, Berliner JG, Goel S, et al. Outcomes of melanoma in situ treated with Mohs micrographic surgery compared with wide local excision. JAMA Dermatol 2017; 153:436-441.
10. Phan K, Loya A. Mohs micrographic surgery versus wide local excision for melanoma in situ: analysis of a nationwide database. Int J Dermatol. 2019; 58(6):697-702.
11. Phan K, Oh LJ, Goyal S, et al. Recurrence rates following surgical excision of periocular basal cell carcinomas: systematic review and meta-analysis. J Dermatolog Treat. 2020; 31(6):597-601.
12. Remiszewski P, Pisklak A, Filipek K, et al. Dermatofibrosarcoma protuberans (DFSP): current treatments and clinical trials. Curr Treat Options Oncol. 2025; 26(11):967-989.
13. Sella T, Goren I, Shalev V, et al. Incidence trends of keratinocytic skin cancers and melanoma in Israel 2006-11. Br J Dermatol. 2015; 172(1):202-207.
14. Sharifi S, Rodriguez I, Antonevich S, et al. Mohs micrographic surgery in female genital cancers: a systematic review. J Drugs Dermatol. 2025; 24(11):1080-1086.
15. Sharma AN, Foulad DP, Doan L et al. Mohs surgery for the treatment of lentigo maligna and lentigo maligna melanoma - a systematic review. J Dermatolog Treat. 2021; 32(2):157-163.
16. Stevens JS, Murad F, Smile TD, et al. Validation of the 2022 National Comprehensive Cancer Network risk stratification for cutaneous squamous cell carcinoma. JAMA Dermatol. 2023; 159(7):728-735.
17. Tolkachjov SN, Kelley BF, Alahdab F, et al. Atypical fibroxanthoma: systematic review and meta-analysis of treatment with Mohs micrographic surgery or excision. J Am Acad Dermatol. 2018; 79(5):929-934.
18. van Loo E, Mosterd K, Krekels GA, et al. Surgical excision versus Mohs' micrographic surgery for basal cell carcinoma of the face: a randomised clinical trial with 10 year follow-up. Eur J Cancer. 2014; 50(17):3011-3020.
19. Williams GJ, Quinn T, Lo S, et al. Mohs micrographic surgery for the treatment of invasive melanoma: a systematic review with meta-analyses. J Eur Acad Dermatol Venereol. 2025; 39(2):416-425.
20. Yadlapati S, Rosa-Nieves PM, Lauck KC, Tolkachjov SN. Mohs micrographic surgery versus wide local excision in the treatment of anogenital squamous cell carcinoma: a systematic review. Int J Dermatol. 2025; 64(6):1042-1048.

Government Agency, Medical Society, and Other Authoritative Publications:

1. American Cancer Society. Melanoma skin cancer. Available at: https://www.cancer.org/cancer/melanoma-skin-cancer.html. Accessed on February 5, 2026.
2. American Cancer Society. Key statistics for Merkel cell carcinoma. Last revised January 10, 2025. Available at: https://www.cancer.org/cancer/types/merkel-cell-skin-cancer/about/key-statistics.html. Accessed on February 5, 2026.
3. Bath-Hextall FJ, Matin RN, Wilkinson D, et al. Interventions for cutaneous Bowen's disease. Cochrane Database Syst Rev. 2013;(6):CD007281.
4. Centers for Disease Control and Prevention. Skin cancer. Available at: https://www.cdc.gov/cancer/skin/index.htm. Accessed on February 5, 2026.
5. Connolly SM, Baker DR, Coldiron BM, et al. AAD/ACMS/ASDSA/ASMS 2012 appropriate use criteria for Mohs micrographic surgery: a report of the American Academy of Dermatology, American College of Mohs Surgery, American Society for Dermatologic Surgery Association, and the American Society for Mohs Surgery. Dermatol Surg. 2012; 38(10):1582-1603.
6. Kim JYS, Kozlow JH, Mittal B, et al. Guidelines of care for the management of basal cell carcinoma. J Am Acad Dermatol. 2018a; 78(3):540-559.
7. Kim JYS, Kozlow JH, Mittal B, et al. Guidelines of care for the management of cutaneous squamous cell carcinoma. J Am Acad Dermatol. 2018b; 78(3):560-578.
8. Narayanan K, Hadid OH, Barnes EA. Mohs micrographic surgery versus surgical excision for periocular basal cell carcinoma. Cochrane Database Syst Rev. 2014;(12):CD007041.
9. National Cancer Institute (NCI). Skin cancer treatment (PDQ^®)-health professional version. Updated May 12, 2025. Available at: https://www.cancer.gov/types/skin/hp/skin-treatment-pdq. Accessed on February 5, 2026.
10. NCCN Clinical Practice Guidelines in Oncology^®. © 2026 National Comprehensive Cancer Network, Inc. For additional information visit the NCCN website: https://www.nccn.org/guidelines/category_1
    Accessed on February 5, 2026.
    • Basal Cell Carcinoma (V.1.2026). September 2, 2025
    • Cutaneous Melanoma (V.2.2025). January 28, 2025
    • Dermatofibrosarcoma Protuberans (V.2.2026). October 25, 2025
    • Merkel Cell Carcinoma (V.2.2026). October 24, 2025
    • Squamous Cell Carcinoma (V.1.2026). September 2, 2025
11. Schmults CD, Blitzblau R, Aasi SZ, et al. Basal cell skin cancer, Version 2.2024, NCCN clinical practice guidelines in oncology. J Natl Compr Canc Netw. 2023; 21(11):1181-1203.
12. Schmults CD, Blitzblau R, Aasi SZ, et al. NCCN Guidelines^® insights: squamous cell skin cancer, version 1.2022. J Natl Compr Canc Netw. 2021; 19(12):1382-1394.
13. Thomson J, Hogan S, Leonardi-Bee J, et al. Interventions for basal cell carcinoma of the skin. Cochrane Database Syst Rev. 2020;11:CD003412.
14. Tzellos T, Kyrgidis A, Mocellin S, et al. Interventions for melanoma in situ, including lentigo maligna. Cochrane Database Syst Rev. 2014;(12):CD010308.

1. Medline Plus. Skin cancer. Last updated August 9, 2025. Available at: https://medlineplus.gov/skincancer.html. Accessed on February 5, 2026.

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