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    • Home
    • What is skin cancer?
      • Overview of skin cancer
      • Basal Cell Carcinoma
      • Squamous Cell Carcinoma
      • Melanoma
      • Merkel Cell
      • Actinic Keratosis
      • Rare types of skin cancer
    • Mohs Surgery
      • What is Mohs Surgery?
      • Your Surgery Day
      • Wound Care Instructions
      • FAQ
    • Wide Excisions
      • What is a Wide Excision?
      • Melanoma Wide Excision
      • How to Prepare
      • Medications to Avoid
      • What To Expect
    • Be sun wise
      • What is sun damage?
      • UVA & UVB
      • Sun protection
      • Sunscreen 101
    • Our Team
      • Dr. Jennifer Guillemaud
      • Heather Harper, NP
      • Dr. Mike Sander
      • The Team
      • Charities We Love
    • Field Therapy
    • Products We Love
    • Contact Us
  • Home
  • What is skin cancer?
    • Overview of skin cancer
    • Basal Cell Carcinoma
    • Squamous Cell Carcinoma
    • Melanoma
    • Merkel Cell
    • Actinic Keratosis
    • Rare types of skin cancer
  • Mohs Surgery
    • What is Mohs Surgery?
    • Your Surgery Day
    • Wound Care Instructions
    • FAQ
  • Wide Excisions
    • What is a Wide Excision?
    • Melanoma Wide Excision
    • How to Prepare
    • Medications to Avoid
    • What To Expect
  • Be sun wise
    • What is sun damage?
    • UVA & UVB
    • Sun protection
    • Sunscreen 101
  • Our Team
    • Dr. Jennifer Guillemaud
    • Heather Harper, NP
    • Dr. Mike Sander
    • The Team
    • Charities We Love
  • Field Therapy
  • Products We Love
  • Contact Us

Calgary Skin Cancer Centre

Calgary Skin Cancer CentreCalgary Skin Cancer CentreCalgary Skin Cancer Centre

MOHS MICROGRAPHIC SURGERY

Dr. Frederic Mohs & The Origins of Mohs Surgery

Mohs Micrographic Surgery was pioneered in the 1930s by Dr. Frederic Mohs at the University of Wisconsin. His goal was to develop a technique that could remove skin cancer with precision—eliminating the tumor while preserving as much healthy surrounding tissue as possible. Today, Mohs surgery is considered the gold standard for treating certain skin cancers, offering the highest cure rates of any method—even when the cancer has recurred or been previously treated by other means. It has a 98% or higher success rate for the two most common types of skin cancer: Basal Cell Carcinoma and Squamous Cell Carcinoma.

What is Mohs Micrographic Surgery?

Mohs Micrographic Surgery is a highly precise and effective technique used to treat certain types of skin cancer. During the procedure, thin layers of skin containing cancer cells are carefully removed one at a time and examined under a microscope. This process is repeated until only cancer-free tissue remains.

The goal of Mohs surgery is to completely remove the cancer while preserving as much healthy tissue as possible. This careful approach minimizes scarring, helps maintain the natural appearance of the skin, and often allows for more refined surgical reconstruction.

One of the unique advantages of Mohs surgery is that it allows for 100% of the tissue margins to be examined in real time, with results typically available within 60–90 minutes. With a cure rate of approximately 99%, Mohs surgery is considered the gold standard for treating many skin cancers, especially those in delicate or high-risk areas.

The Mohs Process

STEP 1: TUMOR MARKING & ANESTHESIA

STEP 1: TUMOR MARKING & ANESTHESIA

The surgeon begins by identifying and carefully marking the visible area of the skin cancer. Although the tumor may appear well-defined on the surface, there is often microscopic spread beyond what can be seen with the naked eye. Once the area is outlined, a local anesthetic is injected to completely numb the skin and surrounding tissue, 

The surgeon begins by identifying and carefully marking the visible area of the skin cancer. Although the tumor may appear well-defined on the surface, there is often microscopic spread beyond what can be seen with the naked eye. Once the area is outlined, a local anesthetic is injected to completely numb the skin and surrounding tissue, ensuring that the patient is comfortable throughout the procedure. This step is essential to guide accurate tissue removal and map the area for microscopic examination later.

STEP 2: TUMOR REMOVAL

STEP 1: TUMOR MARKING & ANESTHESIA

Once the area is completely numb, the surgeon gently removes the visible portion of the tumor using a precise scalpel technique. The surgical site is temporarily bandaged, and the patient can rest comfortably while the tissue is being examined for any remaining cancer cells.

STEP 3: TISSUE MAPPING & PROCESSING

The removed tissue is carefully divided into small numbered sections, or blocks, each representing a specific area around the tumor. These blocks are oriented and mapped to match the surgical site exactly, so if any cancer cells are found, the surgeon knows precisely where they came from. The tissue is then rapidly frozen, stained, and pl

The removed tissue is carefully divided into small numbered sections, or blocks, each representing a specific area around the tumor. These blocks are oriented and mapped to match the surgical site exactly, so if any cancer cells are found, the surgeon knows precisely where they came from. The tissue is then rapidly frozen, stained, and placed onto microscope slides for evaluation. Each tissue block is processed and analyzed individually, ensuring that even the tiniest traces of cancer cells can be detected.

STEP 4: Microscope examination

Step 6: Reconstruction & healing

Using a microscope, the surgeon examines the stained tissue slides to look for any remaining cancer cells. Because the entire margin of the removed tissue is evaluated, this allows for a 100% microscopic assessment—a key advantage of Mohs surgery. If cancer cells are found, the surgeon marks their exact location on the surgical map, ident

Using a microscope, the surgeon examines the stained tissue slides to look for any remaining cancer cells. Because the entire margin of the removed tissue is evaluated, this allows for a 100% microscopic assessment—a key advantage of Mohs surgery. If cancer cells are found, the surgeon marks their exact location on the surgical map, identifying the precise area on the skin where more tissue needs to be removed. This step ensures that only cancerous tissue is targeted in the next stage, while healthy tissue is preserved.

STEP 5: Targeted tissue removal

Step 6: Reconstruction & healing

Step 6: Reconstruction & healing

If any cancer cells are found during the microscopic review, the surgeon will remove only the specific areas where cancer remains—no more, no less. In each additional stage, just 1–2 millimeters of tissue are taken from the affected spots, sparing as much healthy tissue as possible. The removed tissue is then processed and analyzed just l

If any cancer cells are found during the microscopic review, the surgeon will remove only the specific areas where cancer remains—no more, no less. In each additional stage, just 1–2 millimeters of tissue are taken from the affected spots, sparing as much healthy tissue as possible. The removed tissue is then processed and analyzed just like before. This step-by-step approach is repeated—often two to three times—until all tissue margins are confirmed to be clear and cancer-free.

Step 6: Reconstruction & healing

Step 6: Reconstruction & healing

Step 6: Reconstruction & healing

Once all cancerous tissue has been successfully removed and the margins are clear, the Mohs surgeon will evaluate the surgical site and discuss reconstruction options with the patient. The best approach depends on the size and location of the wound. Options may include allowing the area to heal naturally on its own, repositioning nearby s

Once all cancerous tissue has been successfully removed and the margins are clear, the Mohs surgeon will evaluate the surgical site and discuss reconstruction options with the patient. The best approach depends on the size and location of the wound. Options may include allowing the area to heal naturally on its own, repositioning nearby skin (a flap), or using a skin graft from another part of the body. In most cases, reconstruction is completed the same day as the cancer removal. However, if the repair is more complex, the surgeon may refer the patient to another specialist to ensure the best functional and cosmetic result.

Mohs Surgery: The Most Effective Treatment for Skin Cancer

Resource: American College of Mohs Surgery

When Is Mohs Indicated?

Mohs Micrographic Surgery offers the highest cure rate for the removal of practically any type of skin cancer. There are also many other effective treatments for skin cancer including cryotherapy, surgical excision, scraping and burning of the tumour or laser therapy. Each one of these therapies requires the Surgeon to estimate how wide of a margin to treat or remove around the tumour. Some of the advantages to using the Mohs Micrographic Surgery procedure over other skin cancer treatments including its high cure rates. Mohs Micrographic Surgery is indicated when:


  • The tumour is in a cosmetically sensitive area where preserving as much normal tissue as possible is  important to maintain the function and appearance
  • The tumour has recurred after previous treatment
  • Are large
  • The tumour is growing quickly
  • The tumour’s edges are very ill-defined and hard to decipher
  • Are located in scar tissue

To learn about what you can expect on your surgery day, CLICK HERE

Mohs Surgery Before & After

    Resources:

    American College of Mohs Surgery

    Calgary Skin Cancer Centre Moh's Package


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