What is Mohs Surgery? A Philadelphia-Based Dermatologist Explains


According to The Skin Cancer Foundation, one in five Americans will develop some form of skin cancer by the time they are 70. While malignant melanoma can be an aggressive and fatal form of skin cancer, basal cell and squamous cell skin cancers are more common but less aggressive. These non-melanoma skin cancers effect millions of people each year.  Their diagnosis and treatment increased by 77 percent in the country over a recent decade.

Fortunately, an advanced skin cancer treatment method has also been on the rise. The technique is known as Mohs surgery. Philadelphia-based dermatologist Dr. Victoria A. Cirillo-Hyland’s Bryn Mawr Skin & Cancer Institute has two Mohs-trained dermatologic surgeons, Drs. John Mulholland and Kara Capriotti, who treat patients with this precise tissue sparing technique. 

Technically known as Mohs micrographic surgery, the procedure differs from routine surgical excisions in a key way: Tissue is removed one thin layer at a time, with each layer being intensely scrutinized under a microscope during your visit. Traditional excision methods involve removing the cancerous tumor from the skin, along with a certain amount of surrounding tissue, in an effort to capture all of the cancer cells present in the area. Though it can be effective, this approach essentially involves some guesswork. Even a small number of cancer cells overlooked or left behind can multiply and cause a new tumor to form—or even spread beyond the site.

Mohs is a very efficient and effective surgical technique to remove skin cancer. As each layer is removed, the edges—or margins—are examined for signs of cancer cells. If any are present, a new layer is taken and examined. This process is repeated until no cancer cells are visible on any margins. The method allows for an incredibly reliable assessment of the tissue and thorough removal of malignant cells while leaving healthy tissue unharmed.

Because Mohs micrographic surgery is carried out one thin layer at a time, it minimizes the removal of healthy tissue. Once the margins are clear, excision stops, so wounds are only as wide and deep as they need to be. This makes Mohs surgery ideal for cancers on highly visible regions of the face, scalp, neck, ears, and hands.

Minimizing the cosmetic impact of a cancer treatment is ideal, but the biggest factor in choosing how to proceed is the treatment’s effectiveness in removing the cancer. Mohs surgery has a 95 to 99 percent success rate, making it one of the most reliably successful and effective skin cancer treatments available.

Patients interested in Mohs surgery should consult with a board-certified dermatologist who can assess the skin cancer and determine whether it would be the best approach. The skin cancer must meet a set of criteria to be approved (by insurance) for Mohs surgery. The dermatologist will review the following characteristics of the skin cancer to determine if Mohs is the treatment of choice: the type, location, size, microscopic characteristics, prior therapies, and prior radiation treatment to the affected area. Other considerations include the age, health, and medical history of the patient.

If Mohs surgery is not the ideal treatment, other options for skin cancer patients include electrodessication and curettage (scraping and burning the lesion to destroy the cancer cells), traditional excision, radiation therapy, and topical and oral medications.

No matter the treatment chosen, it is best to start it as early as possible. Performing frequent self-skin exams and scheduling regular visits to a dermatologist are crucial components in the fight against skin cancer.  The sooner the skin cancer is identified and treated, the better the cure rate.

Find out more about Mohs surgery for treating skin cancer. Contact Bryn Mawr Skin & Cancer Institute—seeing patients from Bryn Mawr, Newtown Square, and the Philadelphia area—by calling 610.525.5028 or sending a message online.