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Mohs Micrographic Surgery

Mohs Micrographic Surgery is a highly specialized surgical technique best suited for certain high-risk tumors, as well as for those tumors that have occurred in cosmetically and/or functionally sensitive areas that benefit from minimal excision of tissue.

The surgery is named after innovative American surgeon, Frederic Mohs. The Mohs procedure is widely considered as the gold standard for certain types of skin cancers due to its extremely high cure rate while minimizing loss of healthy skin and scarring.

What is the difference between Mohs surgery and “normal” skin cancer surgery?

The main difference between Mohs surgery and other skin cancer surgeries is that Mohs surgery spares as much healthy tissue as possible.

During a routine excision skin cancer surgery, your team will:

Take into consideration the type of skin cancer and the “stage” or severity (in-situ tumor vs. invasive tumor for example) and then estimate a “margin” (i.e. a border of what appears to be unaffected skin around the visible tumor). This margin helps to ensure the tumor is completely removed.

The surgical site is then drawn and designed based on the location and anatomy of the site and the entire area removed.

During Mohs surgery, your team will:

Remove the visible part of the tumor with a very narrow margin of tissue.

Excise the area above and “quadrant” the removed tissue to examine each area for cancer cells.

Continue the process in stages for each quadrant containing cancer cells until all cancerous tissue is removed.

The Advantages of Mohs Surgery for skin cancer

There are several benefits in using the Mohs technique:

Mohs surgery removes all malignant (cancer) cells, including the cells that traditional surgery may overlook due to digging deeper like roots, becoming otherwise difficult to see with traditional surgical and pathology evaluation

Mohs spares the greatest amount of tissue possible from being surgical removed.

Other benefits include:

  • An extremely high cure rate, 98%-99%
  • Minimal scarring
  • Outpatient procedure that typically lasts only several hours
  • Mohs uses local anesthesia thereby lowering the risk of general anesthesia or conscious sedation methods.

Is Mohs Surgery right for me?

The use of Mohs Surgery is guided by the location, type and severity of the skin cancer. Mohs is especially ideal in cases such as:

  • Skin cancer in an area of importance to preserve healthy tissue for functional and cosmetic reasons, including the face, scalp, hands, feet or genitalia
  • Skin cancer is large, aggressive or growing rapidly or uncontrollably
  • Tumor (skin cancer) has recurred (was previously treated and came back)
  • Tumor (skin cancer) has edges or borders that are difficult to determine
  • Tumor (skin cancer) is located on or adjacent to scar tissue

While it is true that Mohs Surgery offers the highest rate of success and best cosmetic outcome, not every skin cancer is a candidate for Mohs Surgery. Some types of tumors (melanoma in particularly) are rarely excised using Mohs Surgery. Furthermore, the American Academy of Dermatology and your insurer have guidelines and locations and situations to which Mohs Surgery is not recommended.

Ultimately, the type of surgery used for your skin cancer is a discussion between you as the patient and your dermatology team. We will discuss your options and always make a recommendation for the approach that will maximize your best outcome. You can learn more about conditions we treat with Mohs surgery.

Tumors Treated with Mohs Surgery

Mohs surgery is most commonly used to treat Basal Cell Skin Cancer, the most common form of cancer in the United States (4-5 million cases annually), as well as Squamous Cell Carcinoma. There are other, rarer, skin cancers / tumors that are also eligible for treatment using Mohs Surgery.

Squamous cell carcinoma (SCC)

Squamous cell carcinoma is the second most common form of skin cancer. SCC has a direct correlation with extensive sun exposure; the most common SCC patient is elderly, fair skin man or women with history of significant sun exposure. SCC rarely spreads (metastasizes); SCC located on the lips and ears, however, do have a known higher risk for metastasis and are always recommended for Mohs Surgery here at The Clinic for Dermatology & Wellness.

Basal cell carcinoma (BCC)

The most common form of cancer in the United States. Basal cell carcinoma starts in the upper layer of the skin (basal cell layer), and is a relatively slow growing form of cancer. BCC rarely spreads to other areas of the body (metastasis).

Dermatofibrosarcoma protuberans (DFSP)

DFSP is a rare skin tumor of unknown cause. DFSP often presents in early to middle adult life (ages 20-55); it is considered to occur less than 1 in every 100,000 people.

Extramammary Paget’s disease (EMPD)

EMPD is a rare form of cancer that often resembles a chronic eczema-like rash near the anogenital or axilla (arm pits) or both men and women. EMPD has a low mortality rate and is readily treated with Mohs Surgery.

Sebaceous carcinoma

Sebaceous carcinoma is a form of cancer of oil glands that join hair follicles. While sebaceous carcinoma is rare, it is often very aggressive. Mohs Surgery is considered the most common and effective form of treatment for this cancer

Microcystic adnexal carcinoma (MAC)

A rare skin cancer. MAC is an often slow growing, rare form of cancer. Often easily treated, failure to successfully treat MAC could result in invasion of nearby fatty tissues. MAC has a high success rate with Mohs Surgery.

What to expect during your Mohs Surgery

Mohs Surgery is a simple outpatient surgical procedure using local anesthesia (i.e. you are not “put under”). This results in your Mohs Surgery being quick with an easy, fast recovery upon the conclusion of your surgery. During your Mohs procedure you can expect:

Step 1: Dr. Tang will surgically remove the area of tumor visible to the naked eye.

Step 2: Next, Dr. Tang will carefully mark the removed tissue in four quadrants for reference and the tissue will be processed into slides.

Step 3: Dr. Tang will then examine the prepared tissue slides under a microscope and will identify each quadrant and area with cancer cells remaining.

Step 4: Steps 2 and 3 are repeated in any quadrant with cancerous tissue. Each iteration of this removal is called a “stage”. The number of stages depends upon the size, location and aggressiveness of the skin cancer, but most tumors are removed in one to two stages.

Step 5: Once all cancer tissue has been successfully removed, Dr. Tang will counsel you at to the best technique to repair the surgical site. Some surgeries are best allowed to heal naturally, from the bottom up (this is called secondary intention). Other sites are best repaired with stitches using a simple layered closers, or advanced techniques such as flaps or tissue grafts from other locations on the body.

Step 6: Your Dermatology provider will work with you to continue skin cancer surveillance by conducting Total Body Skin Exams (TBSE) at an interval best designed based on your type of cancer, history of any previous skin cancers, age, and sun exposure history.

Traditional Skin Cancer Excision

Occasionally, Dr. Tang and your Dermatology Provider will recommend a traditional form of skin cancer treatment, simply called surgical excision (removal). This technique is common for simple, non-aggressive tumors on the torso, arms and legs that do not demonstrate more concerning characteristics. This same procedure (surgical excision) is used on benign lesions such as dysplastic (pre-cancerous) moles, cysts, and benign tumors such as lipomas.

Excisional surgery typically takes 1-hour from time of check in to bandaging the treatment area. While excision requires more healthy tissue to be removed than Mohs Surgery, our skilled surgical teams take great care to offer extremely high cure rates while minimizing scarring from the procedure.

Prior to your excisional surgery, your surgical team will use local anesthesia to prepare the site and prevent any pain or discomfort during your surgery. Then, your surgeon will:

  • Outline the visible area of tumor and then create a “margin” of healthy skin to ensure all remnants of skin cancer are removed. Margin size is determined by the type of skin cancer, its aggressiveness and the location on the body.
  • The surgeon will then surgically remove the drawn area
  • The excised tissue will then be sent to the lab for analysis to ensure that all remnants of the cancer was fully removed (clear margins). This typically takes one week.

Preparing for your Mohs Surgery

Although Mohs Surgery is an outpatient surgical procedure, there are still precautions and steps to perform as the patient that will maximize your comfort and surgical outcome. We are providing the following guidelines to start 2 weeks onwards to prepare for your surgery; you can download here the full guidelines to print. You can also obtain printed guidelines with pre-operative and post-operative care at the Front Desk at the clinic.


Begin these steps 2 weeks prior to surgery:

We know that it’s hard to quit smoking; however, smoking and tobacco use delays wound healing and slows your progress. We ask that you cease smoking two weeks prior to surgery.

Unless they are prescribed, we ask that you stop the following medications 2 weeks before surgery as they can cause excessive bleeding:

  • Aspirin, or products that contain aspirin (e.g., Alka-Seltzer, Excedrin)
  • Ibuprofen (Advil, Motrin)
  • Naproxen (Aleve)
  • Tylenol, or its generic form, acetaminophen, are okay to take if needed.

If you are taking any of the above by prescription, please make sure that the medical staff is aware of your use of these medications and the reason why for your chart and to ensure that the Surgeon is aware of your use.


1 week before surgery

It is important to help minimize the risk of artificially raised blood pressure during surgery. Therefore, we ask that you discontinue the use of:

  • Ginkgo biloba
  • Ginseng
  • Garlic
  • Vitamin E
  • Vitamin C
  • Fish oil
  • Other herbal supplements

24 hours before surgery

To protect against raised blood pressure and increased bleeding, we ask that you not drink alcohol, coffee, or any caffeinated beverage at least 24 hours before and after your surgery.


Day of surgery

On the day of surgery, we ask that you:

  • Please bathe (shower or bath) and ensure that you wash the area of the surgery and your hair
  • Do not use any makeup if your skin cancer is on the face
  • Make sure to take all scheduled, prescribed medications (unless otherwise directed by our medical staff) including blood pressure, diabetes, and cholesterol drugs (we also ask you to bring 1 days supply with you to your surgery)
  • Eat a normal meal during your normal schedule
  • Surgical rooms are kept cool; please wear warm, loose yet comfortable clothes
  • We will have light snacks and drinks available; you should be prepared to spend at least 3-4 hours through the morning or early afternoon. Please bring a book, iPad, or something to occupy your time.

Mohs Surgery Post-operative Care

We request that a family member or friend accompany you on the day of your surgery to provide companionship and to assist you in getting home.

Many people are concerned about pain after their Mohs Surgery; however, for the great majority of patients, post-operative pain is very mild and rarely needs medications beyond Tylenol (acetaminophen).

You will be provided with a thorough booklet of your aftercare instructions.

  • Please keep in mind that it often takes months before final wound healing is complete and the best cosmetic result is obtained.
  • Although, uncommon, bleeding after surgery is the most common potential post-operative complication. To minimize the chances of this occurring, patients are advised to be as minimally active after surgery as possible.
  • No bending or heavy lifting
  • No rigorous exercise or exertion
  • Do not make important plans in the days immediately following your surgery
  • Infection is also a possibility following surgery, but it occurs only in one to two percent of patients. Often a small red area may develop surrounding your wound. This is normal and does not necessarily indicate infection. However, if this redness does not subside, and if the wound begins to drain pus or becomes swollen or very tender, you should notify us immediately.
  • Swelling and bruising are common following Mohs Surgery, particularly when surgery is performed around the eyes. This usually occurs within five to seven days after surgery and may be decreased by the use of an ice pack during the first 24-48 hours.
  • At times, the area surrounding your wound will be numb to the touch. This may persist for weeks or months, and in some instances, can be permanent. This is due to trauma to the small nerve endings in the skin surface that occurs during removal of the tumor.

Mohs Patient Information Package