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Skin Cancer

Mohs Surgery

Mohs surgery, also known as Mohs Micrographic Surgery (MMS), is a technique developed by Frederic Mohs in the 1930s. Tissues from cancerous tumors were treated with a special zinc preparation that preserved the tissue for examination under a microscope (Nehal & Lee, 2023). Today, MMS requires specially trained laboratory technicians, called histotechnologists, who cut and stain fresh tumor tissue collected in the dermatology office for immediate review by the Dermatologic Surgeon (Kauvar, n.d.). Mohs is the gold standard in the treatment of non-melanoma skin cancers, such as basal cell carcinoma (BCC) and squamous cell carcinoma (SCC), with a 99% cure rate (AAD, 2021). This means 99% of the cancerous tumors removed never return.

Your Bliss Dermatology Mohs Surgeon, Dr. Michelle Pennie, is a fellowship-trained and board-certified Micrographic Dermatologic Surgeon.  She is specially trained in the Mohs surgery technique, skin cancer pathology, and reconstructive surgery. To better understand the MMS process, we first need to understand the structure of a skin cancer tumor.

Skin cancer tumors are like icebergs; what you see on the surface is usually 10% or less of the actual tumor (Nehal & Lee, 2023). To completely remove skin cancer with the MMS technique, Dr. Pennie will excise the tumor with a small margin around and underneath the tumor. Once that tissue is removed, it is processed in the onsite Mohs lab by the histotech.  Dr Pennie then examines the tissue under the microscope, identifying any cancer cells and checking the edges of the sample for healthy skin cells. If Dr. Pennie finds all of the cancer cells are not removed, she will remove additional layers of the tumor in a process known as stages. This process continues until no cancerous cells are seen, and only healthy tissue cells are visible, as shown in the graphic below.

Mohs surgery has six (6) basic steps or processes.

  1. Mapping: the tumor is marked by the surgeon with a surgical pen to identify the margins for removal
  2. Removal: the area is numbed with anesthetic, and the visible tumor is excised
  3. Freezing: the tissue is frozen, cut into thin sections, and placed on a microscope slide by the histotechnologist
  4. Staining: the slide is stained using a process specially designed to identify the cancerous cells
  5. Histology Examination: the surgeon views the stained slide under the microscope to look for cancerous cells on the margin of the sample. If cancerous cells are visualized, the surgeon repeats the removal process until the margins of the stained slide are clear of cancer cells.
  6. Reconstruction or Closure: the wound is closed using scar-minimizing techniques. The wound is dressed, and the patient returns home.

Follow-up visits for wound care or to observe wound healing are scheduled a few days to a week after the procedure. Once healed well enough, the sutures are removed.

According to the 2012 Appropriate Use Criteria (AUC) from the Academies for Dermatology, Dermatologic Surgery, College of Mohs Surgery, and Society for Mohs Surgery (2012), MMS is recommended when the cancer is in the following body areas:

  • Mask areas of the face
  • Eyelids or close to the eyes
  • Eyebrows, nose, and lips
  • Chin
  • Ears or temple region
  • Hands, feet, nails, or ankles
  • Nipples or areola
  • Cheeks, forehead, or scalp
  • Jawline or neck
  • Shin or bony prominences of the extremities

Mohs can be performed on aggressive, nodular, or superficial recurrent basal cell cancer, aggressive or primary squamous cell skin cancer for lesions starting at 0.5cm in diameter, or melanoma in situ — early-stage melanoma that has not spread to the adjacent tissues or other body structures (AUC, 2012). Only you and Dr. Pennie can decide if Mohs surgery is right for you. Make sure to ask questions about your options for the best outcome.

Mohs surgery is a complex process requiring time and patience. Plan to be in the Bliss Dermatology office for several hours. You may want to wear loose-fitting clothing and bring a sweater, reading material, or snacks for your visit. The onsite facilities have a separate waiting room for Mohs patients who are waiting for results in between stages of surgery with coffee, tea, or water, and some light refreshments for your convenience. Make sure to follow the pre-surgery instructions given to you by the team at Bliss Dermatology.

You will be awake for the procedure, and the area will be numbed using a local anesthetic like lidocaine. You will return to the Mohs waiting room after each tissue stage is removed to allow Dr. Pennie time to process and examine your sample under the microscope. A pressure dressing will be placed over the wound to control bleeding and protect you while you wait. Most tumors require one (1) to three (3) stages to excise the tumor, leaving only healthy tissue behind (Ruder, n.d.). Once the tumor is cleared, Dr Pennie and her surgical team will repair the resulting defect to reduce healing time and improve the scar appearance. Depending on the location, size, and depth of the defect, they may choose a linear repair, a flap repair, or a skin graft.  Once the wound has been repaired, a clean pressure dressing is placed, and you may return home. Please bring a driver if your surgery is near your eyes or if the dressing will interfere with your vision. If you need medication to help with anxiety during the procedure, you will need someone to drive you home.

For more information about Mohs surgery, please visit the Mohs College Website.

Schedule a dermatology appointment.

Take control of your skin cancer journey by scheduling a consult with Dr. Michelle Pennie of Bliss Dermatology. A fellowship-trained Mohs surgeon, Dr. Pennie’s expertise in skin cancer is second to none. Don’t wait – prioritize your health and call us today.

At a Glance

Michelle Pennie, MD

  • Board-Certified Dermatologist
  • Fellowship-Trained Mohs Surgeon
  • Founder and Lead Dermatologist of Bliss Dermatology
  • Learn more

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