What is Mohs Surgery? A Comprehensive Guide to Mohs Micrographic Surgery

Mohs surgery, also known as Mohs micrographic surgery, is a highly effective and precise surgical technique for treating skin cancer. It’s distinguished by its meticulous approach of removing skin cancer layer by layer, examining each layer under a microscope until no cancer cells remain. This process ensures the complete removal of the tumor while preserving as much healthy tissue as possible. This article will delve into what Mohs surgery is, why it’s performed, what to expect, and its benefits in treating skin cancer.

Understanding Mohs Surgery

Mohs surgery is named after Dr. Frederic E. Mohs, who developed the technique in the 1930s. It’s considered the gold standard treatment for many types of skin cancer, particularly basal cell carcinoma and squamous cell carcinoma. The unique aspect of Mohs surgery is that it allows for immediate and complete microscopic examination of the removed tissue margins. This real-time analysis during the surgery ensures that all cancerous cells are eradicated before the surgical site is closed.

What is Mohs Micrographic Surgery?

The term “micrographic” in Mohs micrographic surgery highlights the microscopic analysis that is integral to the procedure. Unlike traditional surgery where tissue margins are sent to a lab for analysis after the entire tumor is removed, Mohs surgery incorporates this examination as a crucial step during the operation itself. This meticulous approach minimizes the chance of cancer recurrence and maximizes the preservation of healthy skin, leading to superior cosmetic and functional outcomes.

How Mohs Surgery Works

Mohs surgery is performed in stages, allowing for precise removal of cancerous tissue while safeguarding surrounding healthy skin. Here’s a breakdown of the process:

1. Initial Examination and Preparation: The surgical area is cleaned, and local anesthesia is administered to numb the area, ensuring a pain-free procedure.

2. Surgical Removal of the First Layer: The surgeon removes the visible tumor along with a very thin layer of surrounding tissue. A map of the surgical site is created to meticulously document the exact location of each removed tissue piece.

3. Microscopic Examination: The removed tissue layer is processed and examined under a microscope right in an on-site lab. The Mohs surgeon, who is also trained as a dermatopathologist, carefully analyzes the entire margin of the tissue to check for any remaining cancer cells.

4. Mapping and Identifying Cancerous Areas: If cancer cells are detected under the microscope, their precise location is identified on the surgical map. This targeted approach is a key advantage of Mohs surgery.

5. Removal of Additional Layers (If Necessary): Based on the map, the surgeon removes another thin layer of tissue, but only from the specific area where cancer cells were found. This step is repeated, with microscopic examination after each removal, until no cancer cells are detected in the tissue margins.

6. Wound Closure and Reconstruction: Once the cancer is completely removed, the surgeon will discuss options for wound closure. This may include allowing the wound to heal naturally, closing it with stitches, or, in more complex cases, using a skin graft or flap. The best method depends on the size and location of the wound.

Why Mohs Surgery is Recommended

Mohs surgery is not necessary for every skin cancer case, but it is particularly recommended in situations where precise tissue sparing and high cure rates are critical. Here are key reasons why doctors may recommend Mohs surgery:

Types of Skin Cancer Treated

Mohs surgery is highly effective in treating various types of skin cancers, including:

• Basal Cell Carcinoma (BCC): The most common type of skin cancer, BCC can often be effectively treated with Mohs surgery, especially when it is high-risk, recurrent, or located in cosmetically sensitive areas.
• Squamous Cell Carcinoma (SCC): Another common skin cancer, SCC, especially high-risk variants, benefits from the precision of Mohs surgery to ensure complete removal.
• Melanoma in situ (Lentigo Maligna): An early form of melanoma, Mohs surgery can be used in specific cases.
• Certain Rare Skin Cancers: Mohs surgery can also be utilized for less common skin cancers like dermatofibrosarcoma protuberans and microcystic adnexal carcinoma.

Ideal Candidates for Mohs Surgery

Mohs surgery is often the preferred treatment for skin cancers that exhibit certain characteristics or are located in specific areas:

• High-Risk Skin Cancers: Cancers that are large, aggressive, have indistinct borders, or have recurred after previous treatment are often best treated with Mohs surgery due to its high cure rate.
• Cosmetically Sensitive Areas: For cancers located in areas where preserving appearance and function is important, such as the face (nose, eyes, ears, lips), hands, feet, and genitals, Mohs surgery is ideal. It minimizes the removal of healthy tissue, leading to better cosmetic outcomes and functional preservation.
• Scar Tissue or Areas of Prior Radiation: Skin cancers that develop in scar tissue or areas previously treated with radiation can be more challenging to treat, making Mohs surgery a valuable option.

Preparing for Mohs Surgery

Proper preparation for Mohs surgery can help ensure a smooth procedure and recovery. Your surgeon will provide specific instructions, but general preparation steps include:

Pre-operative Instructions

• Medication Review: Inform your surgeon about all medications and supplements you are taking, especially blood thinners like aspirin, warfarin, or vitamin E, as these may need to be temporarily discontinued to minimize bleeding risk. However, always consult your doctor before stopping any prescription medications.
• Day Planning: Mohs surgery is typically an outpatient procedure, but the duration can be variable depending on the extent of the cancer. Plan to spend the entire day at the clinic or surgical center.
• Comfortable Clothing: Wear comfortable, layered clothing as the temperature in the surgical suite can fluctuate.
• Meals: Unless instructed otherwise, you can usually eat and drink normally before surgery.
• Entertainment: Bring a book, magazine, or other form of entertainment to help pass the time while waiting between stages of the surgery.

What to Expect During Mohs Surgery

Understanding what to expect during Mohs surgery can help alleviate anxiety and prepare you for the process.

The Mohs Procedure Steps

Upon arrival, you will be taken to a procedure room. The area around the skin cancer will be cleaned, and the surgical site will be marked. Local anesthesia will be injected to numb the area. The procedure then follows the staged approach described earlier: removal of a thin layer of tissue, microscopic examination, mapping, and further removal only where cancer is found, repeated until clear margins are achieved.

Pain Management

Mohs surgery is performed under local anesthesia, meaning you will be awake but the surgical area will be completely numb. You should not feel pain during the tissue removal. You may feel some pressure or slight discomfort, but if you experience any pain, inform your surgical team immediately.

Mohs Surgery Risks and Potential Complications

Like any surgical procedure, Mohs surgery carries some risks, although complications are relatively uncommon due to its precise nature.

Common Risks

• Bleeding: Some bleeding is expected after surgery, but it is usually minimal and easily controlled with pressure.
• Pain or Tenderness: Mild pain or tenderness at the surgical site is normal after the anesthesia wears off. Over-the-counter pain relievers can effectively manage this discomfort.
• Infection: Although surgical sites are cleaned to minimize infection risk, infection is still a possibility. Follow your surgeon’s wound care instructions carefully to reduce this risk. Signs of infection include increased pain, redness, swelling, pus, or fever.

Less Common Risks

• Numbness: Temporary or, in rare cases, permanent numbness can occur if small nerve endings are cut during surgery.
• Weakness: If a large skin cancer is removed, especially in areas with underlying muscles, temporary or very rarely permanent weakness can occur if a muscle nerve is affected.
• Scarring: Mohs surgery aims to minimize scarring, but some scarring is inevitable. The extent of scarring depends on the size and location of the wound, as well as individual healing factors.
• Shooting Pain: Some patients may experience temporary shooting pain as nerves regenerate during the healing process.

Recovery and Results After Mohs Surgery

Recovery from Mohs surgery is typically straightforward.

Wound Care and Healing

Your surgeon will provide detailed instructions on how to care for your wound. This typically involves keeping the wound clean and covered with a bandage, changing the bandage daily, and applying an antibiotic ointment if recommended. Healing time varies depending on the size and location of the wound, but most wounds heal within a few weeks.

Immediate Results and Follow-up

One of the significant advantages of Mohs surgery is that you often know the results immediately after the procedure. The goal is to ensure all cancer is removed during the surgery itself. Follow-up appointments may be scheduled to monitor wound healing and for routine skin cancer checks in the future.

Conclusion

Mohs surgery is a highly specialized and effective treatment for skin cancer, offering the highest cure rates for many types of skin cancer while minimizing tissue loss and maximizing cosmetic and functional outcomes. If you have been diagnosed with skin cancer, especially in a high-risk area or with a high-risk tumor, discussing Mohs surgery with a qualified Mohs surgeon is a crucial step in exploring your treatment options. Its precision and meticulous approach make it a valuable tool in the fight against skin cancer, providing patients with peace of mind and excellent outcomes.