If you have a cancerous growth on your skin, your Dermatologist will quickly establish a plan for removal—and they may suggest Mohs surgery. If you aren't familiar with this process, you might have questions. What exactly goes on in a typical skin cancer removal surgery? What is Mohs surgery, and how does it work?

Read on for more information on what to expect from this common, minimally invasive procedure.

Board-Certified Dermatologists: The Skin Surgery Experts

First off, it's important to know that a board-certified Dermatologist is the expert you need to safely remove anything from your skin. Skin surgery is one of the most common things Dermatologists do. They are trained and ready to remove all types of skin growths, including skin tags, warts, cysts, fatty growths, moles of all kinds, and especially skin cancer.

What to Expect the Day of a Procedure

A Dermatologist can usually excise—remove by cutting—most types of skin growth right in their office. For the majority of these procedures, including Mohs surgery, only local anesthesia is needed. This means they will inject lidocaine into the affected area to make sure you can't feel anything during the removal. You'll be awake, comfortable, and able to talk to the Dermatologist while you're having the procedure done—a pretty amazing accomplishment of modern medicine.

Make sure to follow your doctor's pre-procedure instructions to prevent any problems. Most removals take anywhere from 30 minutes up to two hours, and almost always, you can drive yourself to and from the appointment.

An Overview of Skin Cancer Removal

To understand the benefits of Mohs surgery, it's helpful to understand the process behind standard skin cancer removal.

When your Dermatologist removes a cancerous growth, they need to take out a little extra skin around the edges of the growth to ensure total removal. This amount varies from 4 mm to 20 mm depending on the type of cancer, as the abnormal growth can sometimes extend beyond what is visible to the eye. For basal and squamous cell skin cancers (the two most common types), extension beyond the visible edges is usually minimal; only an extra 4 mm to 5 mm of skin around the cancer is removed. In general, taking this amount from the torso, arms, legs, and even parts of the forehead and cheeks will not affect how the final scar will appear. Melanomas, on the other hand, often extend farther beyond what the eye can see, so 10 mm to 20 mm of skin around the entire cancer is removed.

After removal, your Dermatologist carefully sutures your skin to give you the smallest scar possible. Next, the Dermatologist sends the cancer and surrounding skin to a skin pathologist to check that the growth is completely removed. In this scenario, a pathology report usually takes a few days or up to a week to return, meaning you will have to wait to know for sure if all of the cancer is gone. In the vast majority of cases, the cancer is removed completely the first time.

For other places on the body, however, just 4 mm of extra skin removed can make a big difference in how the scar appears. Examples include the nose, the ears, under and around the eyes, and around the mouth. This is where Mohs surgery comes in.

What Is Mohs Surgery?

In the 1930s, a Dermatologist named Frederic Mohs pioneered—and later helped popularize—a different technique in which the skin cancer is excised along with the smallest possible amount of surrounding skin. Dr. Mohs developed a way to quickly analyze the removed tissue on the premises.

Through this process, a Mohs-trained Dermatologist can look at the cancer under a microscope and see whether the removal was complete within an hour or so. You, the patient, simply wait in the office to learn the results. This way, the Dermatologist can remove the minimum amount of skin and check it incrementally resulting in the least visible scar.

Mohs surgery is especially useful for removing trickier basal or squamous cell skin cancers that are irregular in shape, extending out of sight in just one direction. In these instances, the surgeon can bring you back a second or third time (or as many times as needed) to continue to remove from just the cancerous area. Each time, they can quickly process and examine removed tissue to confirm the cancer is gone.

Sometimes, a patient may need to spend hours undergoing repeated rounds in order to achieve complete removal of their cancer, but this is uncommon. The procedure has a 99 percent cure rate for previously untreated cancer, making it both minimally invasive and highly effective.

Trust Your Derm

Your Dermatologist should be your go-to resource for any skin concerns and especially growth removal. Most times, the removal will be a quick, simple procedure that will have you out of the office and home fairly quickly. When your Dermatologist suggests Mohs surgery to remove cancer and do the pathology work in the same visit, know that they're keeping your best cosmetic outcome in mind. Although this might take up more of your day, it is worth the wait to ensure total removal with the smallest of scars.

Finally, keep in mind that despite innovative procedures and promising success rates, prevention is the best medicine for skin cancer—especially if you have or have had growths in the past. Daily use of broad-spectrum SPF 30+ sunscreen and annual skin exams with your Dermatologist can prevent new damage and help catch problems early, keeping you—and your skin—healthy.


  • Lawrence J Green, MD

    Dr. Lawrence Green is an award-winning Dermatologist and clinical professor of dermatology at George Washington University School of Medicine. Based in Rockville, MD, he is the author of over 50 publications in peer-reviewed journals and a member of the Board of Directors of the American Academy of Dermatology.