Mohs surgery comes under the microscope


This is the fourth article in a six-part series that focuses on areas where dermatology is vulnerable, and how members can take action to preserve the ability to practice the full scope of dermatology for the benefit of patients. Watch for the Adapt, Commit, Thrive (ACT) logo in the next two issues of Member to Member to keep abreast of the critical issues facing the specialty in light of health system reform implementation.


By Glenn Goldman, MD

Mohs micrographic surgery is facing scrutiny due to increased utilization. The use of Mohs surgery is increasing more rapidly than is the incidence of skin cancer, and this is an area of concern for payers. The value of Mohs surgery in treating skin cancer, reimbursement for the procedure, and our continued ability to perform Mohs surgery are, in a manner of speaking, under the microscope. 

Changes in the rules for in-office ancillary services, driven by rising utilization of dermatopathology codes, could put Mohs surgery into a regulatory gray zone. However, as dermatologists, we can affect change in this area by making sure we are using Mohs surgery only when it’s appropriate. Some lesions treated using Mohs surgery may be treated effectively with other means.

Focus on trunk and extremities

Not only has the utilization of Mohs surgery risen in recent years, but utilization for CPT code 17313, for Mohs performed on the trunk and extremities, has increased more than 10 percent in the past two years. Most Mohs surgery is performed on the head and neck, but there is concern from payers that smaller tumors on the trunk and extremities could be treated with less-expensive and equally effective modalities.

Medicare will consider reimbursement for Mohs surgery for accepted diagnoses and indications. The current accepted diagnoses and indications are listed in your Medicare Local Coverage Determination (LCD). Mohs surgery indications on the trunk and extremities include aggressive histology; large size; location on the shin, hand, foot, or digits; perineural invasion; positive margins on prior excision; and immunosuppression.

The importance of documentation

The Mohs surgeon must clearly and appropriately document in the patient medical record to indicate that the diagnosis is appropriate for Mohs surgery. Documentation must clearly show that Mohs surgery was chosen because of the complexity (e.g., prior treatment), size, or location (e.g., location in the H-zone of the face, shin, hand, etc.), and that Mohs surgery was the most appropriate choice for treatment of a particular lesion.

Medicare has published MLN SE1318, “Guidance to Reduce Mohs Surgery Reimbursement Issues,” to provide further clarification.

Noridian Administrative Services (NAS), which represents Jurisdiction E (WA, OR, MT, ID, WY, ND, SD, UT, AZ, AK) and F (CA, NV, HI, AS, MP, GU) has adopted the indication from MLN SE1318 as part of the clinical documentation requirements for Mohs surgery. They state, “The surgeon must describe the histology of the specimens taken in the first stage. That description should include 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. There is no need to repeat the detailed description documented for the first stage, presuming that the description would fit the tumor found on subsequent stages.”

See "Cracking the Code: Mohs Clinical Documentation" for an overview of MLN SE1318.

Note: Mohs surgeons in other regions should check their local Medicare carrier LCD to see if and when these changes will be applied to your LCDs.

The following are examples of appropriate use and non-use of Mohs surgery:

Example 1: An immunosuppressed renal transplant patient presents with a 1.2 cm nodular squamous carcinoma on the dorsum of the forearm.

The lesion is located in AUC area L. The patient is immunocompromised and the lesion is greater than 1.1 cm. The use of Mohs surgery is appropriate.  

Example 2: A patient presents with a 1.7 cm keratotic plaque of the right shin.

A preoperative biopsy confirms invasive squamous cell carcinoma. The lesion is located in AUC area M and is an invasive squamous cell carcinoma. The use of Mohs surgery is appropriate.

Example 4: A patient presents with a melanoma in situ of the right medial cheek.

The lesion is in area H. Mohs surgery is appropriate, however, you must check with your carrier to see if it is covered for this indication. Some local medical review policies (LMRP) support the use of Mohs surgery for melanoma in situ, and others do not.

Example 5: A patient presents with a well-defined 1.0 cm biopsy-proven nodular basal cell carcinoma of the right arm.

The lesion is in area L. The indication is not appropriate for Mohs surgery. Alternative methods of treatment should be employed. 

Example 6: A patient presents with a 7 mm keratotic lesion on the glabella.

The pathology reveals actinic keratosis with focal in situ squamous carcinoma.The lesion is in area H, but the indication is not appropriate for Mohs surgery. Alternative methods of treatment should be employed. 

Example 7: A patient presents with a 9 mm keratotic plaque of the right index finger.

A skin biopsy reveals in situ squamous cell carcinoma.The lesion is in area H. Mohs surgery is appropriate. In some cases curettage would be appropriate, and the use of Mohs surgery is a judgment call. 

Example 8: A patient presents with a 4 cm pink patch on the back.

A biopsy reveals superficial basal cell carcinoma. The lesion is in area L. Superficial basal cell carcinoma is not considered an appropriate use for Mohs surgery in area L. An alternate modality should be utilized.

Appropriate use criteria

To help guide members about when it’s appropriate to use Mohs surgery, the AAD has developed Mohs surgery appropriate use criteria (AUC) in conjunction with American College of Mohs Surgery, American Society for Mohs Surgery, and the American Society for Dermatologic Surgery Association. The eight examples listed above are based on these criteria. 

Recently, the Academy developed a Mohs Surgery AUC App for Apple mobile devices to aid in making decisions at the point of care. This tool is designed to improve the quality, efficiency, and cost-effectiveness of the care we provide.

In addition, the Academy has created an Appropriate Use Criteria Committee, whose mission is to “promote and advance the development of appropriate use criteria related to diagnostic, prognostic, and therapeutic options in the assessment and treatment of dermatologic conditions,” to develop future recommendations. 

With your help, as well as the resources the Academy has provided, we are in a good position to demonstrate that dermatologists are good stewards of the health care resources available to us, especially when it comes to Mohs surgery.

Dr. Goldman is professor and chief of dermatology at Fletcher Allen Health Care/University of Vermont College of Medicine. He also is a member of the Academy's Resource-Based Relative Value Scale Committee.

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Appropriate Use Criteria Committee members

 Name  Title Term 
Suzanne Marie Connolly, MD
 Chair  2017
Jane Margaret Grant-Kels, MD
 Member  2017
Clifford Warren Lober, MD, JD
 Member  2017
Carl A. Johnson, MD
 Member  2015
Mark D. Kaufmann, MD
 Member  2015
An-Wen Chan, MD, PhD
 Member  2014
Heidi Tewich Jacobe, MD
 Member  2014
Wendy Smith-Begolka
 Staff liaison  2025