Clinical UM Guideline


Subject: Mohs Micrographic Surgery
Guideline #: CG-SURG-90 Publish Date:    10/17/2018
Status: New Last Review Date:    09/13/2018


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.

Clinical Indications

Medically Necessary:

Mohs micrographic surgery is considered medically necessary for the treatment of basal cell carcinoma, squamous cell carcinoma, melanoma in situ (Stage 0; including lentigo maligna), when the following criteria are met:

  1. The lesion or tumor meets any of the following:
    1. Any of the following combinations of anatomic location and size:
      1. At least 20 mm on trunk and extremities (excluding pretibial region, hands, feet, and ankles); or
      2. At least 10 mm on scalp, neck and pretibial region; or
      3. Any size, on the face (central face, cheeks, forehead, eyelids, eyebrows, periorbital, nose, lips, chin, mandible, preauricular and postuaricular skin/sulci, temple, ear), genitalia, hands or feet; OR
    2. Any of the following clinical presentations regardless of anatomic region:
      1. Deeply infiltrating lesion or difficulty estimating depth of the lesion; or
      2. Perineural invasion; or
      3. Poorly-defined borders; or
      4. Positive margins on recent excision; or
      5. Rapidly growing lesions in any anatomic area; or
      6. Recurrent lesion; OR
    3. Lesions or tumors with aggressive histologic features or at high-risk for recurrence; OR
    4. Tumors associated with a high-risk of metastasis arising in any of the following areas:
      1. Chronic fistulas, sinuses or ulcers (including sinuses of osteomyelitis); or
      2. Chronically inflamed or previously traumatized skin (such as epidermal atrophy or scars/burn scars, post-traumatic wounds, pressure sores/ulcers, ); or
      3. Therapeutic radiation injury; OR
    5. Individual has either of the following:
      1. Genetic syndrome (such as basal cell nevus syndrome or xeroderma pigmentosum); or
      2. Immunocompromised condition (such as hematologic malignancy, human immunodeficiency virus [HIV], organ transplantation, or pharmacologic immunosuppression).   

Mohs micrographic surgery is considered medically necessary for the treatment of the following less common cutaneous tumors or lesions when the following criteria are met:

  1. The lesion to be treated is known to be any of the following:
    1. Adenocystic carcinoma
    2. Adnexal carcinoma
    3. Apocrine/eccrine carcinoma
    4. Atypical fibroxanthoma
    5. Bowenoid papulosis
    6. Dermatofibrosarcoma protuberans
    7. Extramammary Paget disease
    8. Leiomyosarcoma
    9. Malignant fibrous histiocytoma/undifferentiated pleomorphic sarcoma
    10. Merkel cell carcinoma
    11. Microcystic adnexal carcinoma
    12. Mucinous carcinoma
    13. Sebaceous carcinoma

Not Medically Necessary:

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


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.




Mohs micrographic technique, including removal of all gross tumor, surgical excision of tissue specimens, mapping, color coding of specimens, microscopic examination of specimens by the surgeon, and histopathologic preparation including routine stain(s) (eg, hematoxylin and eosin, toluidine blue), head, neck, hands, feet, genitalia, or any location with surgery directly involving muscle, cartilage, bone, tendon, major nerves, or vessels [includes codes 17311, 17312]


Mohs micrographic technique, including removal of all gross tumor, surgical excision of tissue specimens, mapping, color coding of specimens, microscopic examination of specimens by the surgeon, and histopathologic preparation including routine stain(s) (eg, hematoxylin and eosin, toluidine blue), of the trunk, arms, or legs [includes codes 17313, 17314]


Mohs micrographic technique, including removal of all gross tumor, surgical excision of tissue specimens, mapping, color coding of specimens, microscopic examination of specimens by the surgeon, and histopathologic preparation including routine stain(s) (eg, hematoxylin and eosin, toluidine blue), each addition block after the first 5 tissue blocks, any stage



ICD-10 Diagnosis



Merkel cell carcinoma


Other and unspecified malignant neoplasm of skin


Merkel cell carcinoma


Malignant neoplasm of other connective and soft tissue


Malignant neoplasm of vulva


Malignant neoplasm of penis


Malignant neoplasm of scrotum


Melanoma in situ


Carcinoma in situ of skin [Bowen's disease]


Carcinoma in situ of vulva


Carcinoma in situ of penis


Carcinoma in situ of scrotum


Xeroderma pigmentosum


Other specified congenital malformation syndromes, not elsewhere classified [specified as basal cell nevus syndrome]


Asymptomatic human immunodeficiency virus [HIV] infection status


Personal history of leukemia


Personal history of other malignant neoplasms of lymphoid, hematopoietic and related tissues


Personal history of immunosuppression therapy


Transplanted organ and tissue status

Discussion/General Information

According to the American Cancer Society (ACS; 2018), skin cancer is the most common cancer diagnosis in the United States. The majority of skin cancers are basal cell carcinoma (BCC) or squamous cell carcinoma (SCC).  There are approximately 5.4 million basal and squamous cell skin cancers diagnosed each year, of which about 80% are BCC. 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 2018, about 91,270 cases of melanoma will be diagnosed in the U.S. and about 9000 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 1500 new cases diagnosed annually. DFSP is relatively uncommon and slow growing, but is locally aggressive with a high recurrence rate.

Treatments for skin cancer include:  1) topical therapies such as creams, 2) locally destructive techniques such as cryotherapy, 3) curettage and electrodesiccation, 4) radiotherapy, 5) surgical excision with margin evaluation, and 6) Mohs micrographic surgery (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 patient 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.

Advantages of the MMS procedure are 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 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.

Cochrane systematic reviews of the literature on cutaneous Bowen’s disease (Bath-Hextall, 2016), periocular BCC (Narayanan, 2014) and melanoma in situ (Tzellos 2016) searched for but did not identify any randomized controlled trials (RCTs) evaluating MMS.

Van Loo and colleagues (2014) published an RCT with long-term follow-up comparing MMS and surgical excision in 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 versus surgical excision in individuals with recurrent BCC, but not primary BCC. Among individuals with recurrent BCC, the 10-year cumulative probability of recurrence was 3.9% (95% confidence interval [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). 

In 2013, Lansbury and colleagues published a systematic review of observational studies evaluating interventions for non-metastatic squamous cell skin cancer. 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 2017 study by Nosrati and colleagues evaluated outcomes in individuals with melanoma in situ who were treated with MMS (n=277) or wide local excision (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 and scalp/neck whereas wide local excision 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 15-year recurrence rate was 5.0% (95% 1.4% to 3%) in the MMS group and 7.3% (4.8% to 11.0%) in the WLE group. There was not a statistically significant difference in the overall survival 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). 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.

Several guidelines from the National Comprehensive Cancer Network (NCCN) have addressed MMS treatment of various skin cancers. The BCC guideline (V.1, 2018) stated MMS is the preferred surgical technique for high-risk basal cell skin cancer. An alternative recommended procedure is excision with complete circumferential peripheral and deep margin assessment (CCPDMA) with permanent section analysis or intraoperative frozen analysis. As part of the rationale for the guideline, the authors cite the RCT by van Loo and colleagues, described above, 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.

High-risk BCC was defined as:

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

The NCCN SCC guideline (V.2, 2018) recommended MMS for high-risk SCC and stated that CCPDMA is another treatment option. For SCC, the cutoff for considering other treatment modalities is when at least 6 mm clinically tumor-free margins can be obtained without significant anatomic or functional distortions. Evidence cited in the guideline includes a 1992 meta-analysis which found local recurrence rates of 3.1% for primary cutaneous SCC and 10% for recurrent cutaneous SCC, after up to 5 years of follow-up.

In the SCC guideline, the high-risk location and size criteria are the same as for BCC (listed above). The list of “other risk-factors” are somewhat different from the BCC list, as follows:

The NCCN also addressed less common skin cancers. The Merkel Cell Carcinoma guideline (V.1. 2018) states:

Wide local excision with 1- to 2-cm margins to the investing fascia layer remains the standard surgical technique. Mohs surgery, modified Mohs surgery, or complete circumferential peripheral and deep-margin assessment (CCPDMA) may be considered if tissue-sparing is critical, such as for facial MCC.

The Dermatofibroscarcoma Protuberans (V.1, 2018) guideline states:

Some form of complete histologic assessment of all surgical margins before reconstruction is preferred…Mohs or modified Mohs surgery, and traditional wide excision, typically with 2- to 4-cm margins to investing fascia that are subsequently verified to be clear by traditional pathologic examination, are all methods to achieve complete histologic assessment.

The NCCN melanoma guideline (V.2, 2018) does not include specific recommendations regarding use of MMS.

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

In 2012, the American Academy of Dermatology/American College of Mohs Surgery/American Society for Dermatologic Surgery Association/ and the American Society of Mohs Surgery 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%) in appropriate. Regarding melanoma in situ and lentigo maligna, treatment with MMS was considered appropriate if lesions occurred in Area H or Area M. In addition, MMS was considered appropriate for primary lesions in Area L, but not for locally recurrent lesions. (See Definitions section for explanation of Areas H, M and L).


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

Areas of the body per National Comprehensive Cancer Network:

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. 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.

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


Peer Reviewed Publications:

  1. Bath-Hextall FJ, Matin RN, Wilkinson D, et al. Interventions for cutaneous Bowen's disease. Cochrane Database Syst Rev. 2013;(6):CD007281.
  2. 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):211-8.
  3. 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.
  4. Narayanan K, Hadid OH, Barnes EA. Mohs micrographic surgery versus surgical excision for periocular basal cell carcinoma. Cochrane Database Syst Rev. 2014:(12):CD007041.
  5. 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.
  6. Tzellos T, Kyrgidis A, Mocellin S, et al. Interventions for melanoma in situ, including lentigo maligna. Cochrane Database Syst Rev. 2014:(12):CD010308.
  7. 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.

Government Agency, Medical Society, and Other Authoritative Publications:

  1. Centers for Disease Control.  Skin Cancer. Available at: Accessed on June 11, 2018.
  2. 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):1582-603.
  3. Kim JYS, Kozlow JH, Mittal B, et al. Guidelines of care for the management of basal cell carcinoma. J Am Acad Dermatol. 2018a Mar; 78(3):540-559.
  4. Kim JYS, Kozlow JH, Mittal B, et al. Guidelines of care for the management of cutaneous squamous cell carcinoma. J Am Acad Dermatol. 2018b Mar; 78(3):560-578.
  5. National Cancer Institute (NCI). Skin Cancer Treatment (PDQ®)–Health Professional Version. Available at: Accessed on June 12, 2018.
  6. NCCN Clinical Practice Guidelines in Oncology®. © 2018 National Comprehensive Cancer Network, Inc. For additional information visit the NCCN website: Accessed on June 8, 2018.
    • Basal Cell Carcinoma (V.1.2018).
    • Dermatofibrosarcoma Protuberans (V1.2018).
    • Melanoma (V.2.2018).
    • Merkel Cell Carcinoma (V.1.2018).
    • Squamous Cell Carcinoma (V.2. 2018).
Websites for Additional Information
  1. Medline Plus. Skin Cancer.  Available at: Accessed on June 12, 2018.






Medical Policy & Technology Assessment Committee (MPTAC) review. Initial document development.