MOHS Surgery vs Excision

Mohs Surgery vs Excision: Benefits, Side Effects, Advantages, and Disadvantages

According to the American Academy of Dermatology, skin cancer is the most common cancer in the United States, affecting more than 3 million Americans yearly. In addition, nonmelanoma skin cancer (NMSC), including basal cell carcinoma (BCC) and squamous cell carcinoma (SCC), are the most common types of skin cancer. Although melanoma cancer has been on the rise for the last three decades, about one million people in the U.S. are diagnosed with melanoma with a more significant percentage of incidences affecting ages 80 and older. Here’s where we should talk about MOHS Surgery vs Excision.

Surgery is often the recommended approach to treating these types of cancer. However, the kind of surgery ideal for skin cancer will depend on several factors, including the tumor’s size, location, and aggressiveness. The two primary surgical treatments for skin cancer are Mohs Surgery and Excision. This article will provide an overview of each procedure, its uses, side effects, benefits, and when one may be preferred.

What Is Mohs Surgery?

Mohs surgery, or micrographic surgery, is a specialized, tissue-sparing method of treating skin cancer, named in honor of technique developer Dr. Frederic E. Mohs. The surgical procedure provides a high cure rate for removing high-risk skin cancers, such as basal and squamous cell carcinomas.

It is a precise and effective microscopic control treatment that removes thin layers of cancerous tissue. The physician removes the tissue layer by layer, examining each new layer under a microscope for confirmation that all cancerous cells have been removed. If the cancer extends beyond the margins, they should remove and examine more tissue in that location. You must repeat the process until the area is completely clear of cancerous cells. This will allow the doctor to remove the least amount of healthy tissue possible while ensuring that all cancerous cells have been removed.

what is mohs

Why Is Mohs Performed?

According to National Center for Biotechnology Information (NCBI), Mohs surgery is typically beneficial when the risk of skin cancer recurrence after treatment is high. Also, when the patient has a large tumor or a tumor that has spread to adjacent tissue. MOHs can also be used when tissue conservation is crucial, especially body tumors located in the ”H” area (the head, neck, hands, feet, and genital area) and cosmetically sensitive areas, such as the face. In addition, it is better for cases where a high risk of cancer recurrences, such as when the patient has advanced skin cancer or multiple tumors.

Mohs surgery can also treat tumors previously treated with topical or radiation therapies and for areas where preserving the maximum amount of healthy tissue is essential. This includes the nose, ears, eyelids, and lips.

Benefits of Mohs Surgical Procedure

Alongside providing a high cure rate of about 98% to 99%, Mohs surgery offers several benefits often not found in other surgical techniques. These include:

  • Maximum tissue conservation
  • High cure rate and lower risk of recurrence
  • Enhanced ability to accurately map the extent of tumor growth
  • Reduced pain, scarring, disfigurement, and deformity associated with the removal of healthy tissue
  • The minimally invasive procedure with confined surgical margins
  • Ability to remove tumors in difficult-to-access areas, such as the nose and eyelids
  • Reduced risk of infection due to the precise technique

What Should You Expect Before and During a Mohs Surgery?

MOHs surgery is an outpatient setting procedure that takes several hours to complete and is usually used under local anesthesia. During the process, the doctor will prepare, drape, and anesthetize the area and then identify the lesional tissue by stretching the surrounding skin. Using a gentian violet skin-marking pen, the doctor outlines the region and marks the edges. Then, the clinical extent of the tumor is roughly based on the curettage of the tumor bed and a frozen section. Subsequently, the tissue is incised with a sharp 15-blade at a horizontal 45-degree angle, and the tissue is then excised.

The removed skin sample is then processed for HE staining, frozen sectioning, and paraffin embedding. The tissue processing allows for the examination of the margins under high-powered microscopy. If cancer cells are present at any margin, the defect is re-excised according to a pre-determined plan.

MOHS surgery process

After the Surgery

After the defect is removed and measured, the wound dimension is obtained, and a Mohs micrographic surgery map is drawn. A sterile ointment is then applied to the wound site, and the patient is discharged with a pre-specified set of instructions for postoperative care.

The doctor may also fix the wound by stitching it to close it up or use a skin graft to cover the defect. Sometimes, the doctor may recommend reconstructive surgery to improve function and/or cosmetic appearance. Although reconstructive surgery is the last stage of the MOHs procedure, it is a rare occurrence.

Depending on the wound size, the healing process for MOHs surgery, depending on the wound size, typically takes 7 to 21 days. Keeping the wound clean and dry and protecting it from sunlight is essential. Your doctor will provide more specific instructions for care during recovery.

Side Effects of Mohs Surgery

In any medical procedure, there are risks and potential side effects. According to Mayo Clinic, there are surgical risks that may occur after the procedure, such as:

  • Wound infection
  • Suture reaction (if sutures are used to close the wound)
  • Temporally bleeding and/or hematoma formation
  • Tenderness or pain in the affected area.

Less common side effects include:

  • Nerve damage that may lead to permanent weakness of the affected area
  • Scarring or deformity of the affected area
  • Permanent hair loss in the treated area
  • Change in the pigmentation of the skin (lightening or darkening).

It is important to note that these side effects are rare and usually temporary. Your doctor will provide specific instructions on caring for your wound and advise when it is safe to return to normal permanent numbness of the skin and scars. However, working with an experienced and skilled dermatologist will help minimize these risks. Ensure your physician is certified and fellowship-trained by the American College of Mohs Surgery.

What Is Excision?

Surgical excision, or excisional biopsy, is the traditional surgical approach to removing malignant moles, lesions, and other skin cancers. The procedure involves cutting out the entire tumor and a margin of healthy tissue around it. The area is then stitched closed and sent for laboratory examination to check that all cancer cells have been removed. Surgical excisions can be performed to treat benign and malignant skin tumors, including moles, melanomas, basal cell carcinomas, squamous cell carcinomas, and other types of cancer. Compared to MOHs surgery, the excisional biopsy cure rate is lower and has the likelihood of recurrence.

what is excision

Who Performs Excision?

An excisional biopsy can be performed by general surgeons, physicians who can carry out procedures like cholecystostomies and appendectomies. Some of the specialists who may perform the procedure include:

  • Orthopedic surgeons – specialize in the musculoskeletal system
  • Cardiothoracic surgeons – specialize in surgery of organs inside the thorax (the chest)
  • Neurosurgeons- specializing in the treatment of the central and peripheral nervous system, including surgical treatment of brain tumors
  • Surgical oncologists- specialize in tumor removal
  • Plastic surgeons specialize in reconstructing tissue loss or defects due to trauma, surgery, illness, and congenital defects.

Like the Mohs surgery, the excision procedure is done under local anesthesia in a surgical setting, office, or outpatient clinic. The biopsy is usually done as an outpatient procedure, meaning you won’t need to stay in the hospital overnight.

Types of Tumors Best Treated With Excision

A wide excision (elliptical excision) is the most common type of surgical removal for benign and malignant skin lesions. It is performed on various skin cancers, including moles, melanomas, basal cell carcinomas, squamous cell carcinomas, and other types of tumors. Excisional biopsy is especially beneficial for atypical moles as it removes the entire mole, allowing for accurate examination of all margins and removing all cancer cells. Below is an overview of some of the tumors best treated with Excision:

Basal Cell Carcinoma (BCC):

BCC is one of the most common forms of skin cancer that begins in the basal cell (A skin cell continuously produces new skin cells as the old ones at the surface die off). At first, the BCC skin cancer appears as small, fleshy bumps or nodules. It can also appear like growth with slightly elevated, open sores, red patches, pink growths, or scars. The lesions may ooze, crust, itch, or bleed as they grow. While BCC may look different from one person to another, it commonly develops on areas of the body that receive a lot of sun exposure, such as the face, neck, and hands. 

Squamous Cell Carcinoma (SCC):

Squamous cell carcinoma is an aggressive type of skin cancer caused by the overproduction of squamous cells that make up the middle layers of the skin. SCC is caused by exposure to carcinogens, including ultraviolet radiation from sunlight or tanning beds. Although it is not life-threatening cancer, getting the lesion diagnosed and treated for risk of spread is essential. Some common signs of SCC include wart-like growths, rough patches, flat lesions with scaly surfaces, and/or elevated growths. 


Melanoma is an aggressive form of skin cancer that begins in melanocytes (skin cells responsible for skin color). It usually appears on the body as a dark-colored bump or spot but may present in other forms, such as a mole. Melanoma can be detected early by regular self-exams and professional skin exams. While the exact cause of melanoma is unknown, it usually occurs due to sun exposure, immune suppression, or genetics. 

Atypical Moles: 

These are also known as dysplastic nevi and are often larger than typical moles (6 mm or greater) with irregular borders and color. They can be flat or raised and lighter or darker than normal moles. Although Atypical moles are usually benign, they can develop into skin cancer, so it is essential to get them monitored and removed if necessary. Excisional biopsy is the most effective way to remove atypical moles, as it removes the entire mole.

types of tumors

Benefits of Excision

As with Mohs Surgery, Excisional biopsy offers several benefits often not found in other surgical techniques. These include:

  • Shorter procedure time 

While it may depend on the actual size of the tumor, an excisional biopsy may take about 30 to 90 minutes to complete. 

  • Suitable for many types of skin cancers and areas of the body 

An excisional biopsy can treat a wide range of tumors, including moles, melanomas, BCCs, SCCs, and other forms of cancer. This makes it a suitable choice for many types and areas of the body. 

  • Does not require a specialized surgeon 

As earlier stated, a general surgeon can perform the procedure. This can be an advantage, especially for those who find it difficult to access a specialized surgeon. 

Risks Associated With Excision Surgery

Despite its numerous benefits, several risks associated with excisional biopsy must be considered before the procedure. These include: 

  • Scarring – Excision surgery can be associated with large scars, depending on the size and location of the lesion. The scar is usually visible for several months after surgery but can fade over time. 
  • Incomplete removal of cancerous tissue – There is always a risk that some cancer cells may remain even after an excisional biopsy. This is why it is essential to have the procedure performed by a qualified and skilled surgeon. 
  • Damage to surrounding tissue – During the procedure, there is always the risk of damage to nearby nerves, tendons, or other tissues. Additional surgery may be needed to repair or restore function if this happens.
  • Higher chance of recurrence – As mentioned earlier, excisional biopsy has a lower cure rate than Mohs surgery. This means there is a higher chance of the tumor returning after treatment. 

Working with an experienced surgeon who can accurately diagnose and treat the tumor is essential to minimize the risk of recurrence and ensure the complete removal of cancerous cells.

Mohs Surgery vs Excision: Advantages of Mohs Surgery over Excision

When comparing the two treatments, Mohs surgery is usually preferred over excision for skin cancer treatment. The main advantages of this technique include:

Higher Cure Rate

The success rate for Mohs surgery is 99% for high-risk nonmelanoma skin cancers, compared to excisional techniques’ cure rate, which ranges from 90% to 95%.

Reduced Risk of Recurrence

The precise microscopic control treatment of Mohs surgery aims to eliminate cancerous cells before closing the wound, reducing the risk of cancer recurrence rate.

Same-Day Procedure

It only takes less than 30 minutes to remove each tissue. The rest of the time is used to examine the tissue under a microscope to ensure no cancer cells have been left behind.

Maximum Tissue Conservation

Mohs surgery is designed to remove the least amount of healthy tissue possible. This makes it especially beneficial for tumors in cosmetically sensitive areas, such as the face and scalp, where preserving as much normal tissue as possible is desired.

Rapid Recovery Time

The Mohs surgery recovery time is typically less than that of an excisional biopsy. The wound usually takes about 7–21 days to completely heal, compared to 4–6 weeks after surgical excision.

Reduced Pain and Scarring

MOHs surgery is performed under local anesthesia, reducing the amount of pain and discomfort experienced by the patient. It only takes less than 30 minutes to complete the procedure, while the longest part of the process is waiting for the tissue to be analyzed under a microscope. The precision with which the procedure is performed also helps to reduce scarring.

Advantage of MOHS

Disadvantages of MOHS Surgery

Although Mohs surgery is an effective method for treating skin cancer, there are several drawbacks associated with the procedure. These include:

Frozen Section Quality

The accuracy of the frozen sections, which determine the presence or absence of cancer cells, is lower than that of standard histopathological sections. This can lead to an inaccurate assessment of tissue margins and recurrence rates.

Holes in Fragmented Tissue Margins

Although the technique aims to preserve as much healthy tissue as possible, holes in fragmented tissue margins can occur due to the precision of cutting and re-cutting around tumor margins.

Tissue Orientation Problems

Due to the precision required in tissue freezing and sectioning, tissue orientation problems can occur during processing. This can lead to difficulty interpreting results or an inaccurate assessment of margins.

Excessively Narrow or Wide Margins

The technique requires high precision when measuring and cutting the tissue. If the margins are excessively narrow or wide, it can lead to an inaccurate assessment of margins and recurrence rates.

Longer Procedure Time Compared to Other Skin Cancer Removal Procedures

While removing the tissue may take a few minutes, the longest part of the process is waiting for the tissue to be analyzed under a microscope. This can take several hours, increasing the total procedure time. And when there are more cancerous cells to remove, the procedure may take even longer.

Requires a Specialized Surgeon Who Is Trained in the Technique

Due to the complexity and precision of Mohs surgery, it demands a surgeon who is specifically trained in the technique. As stated earlier, it is crucial to ensure the physician performing the procedure is board-certified by the American College of Mohs Surgery.

Not Suitable for All Types of Skin Cancer or All Areas of the Body

Mohs micrographic surgery is only ideal for high-risk nonmelanoma skin cancers, such as basal cell carcinomas and squamous cell carcinomas. One of the main reasons Mohs is ineffective for far more aggressive forms of cancer like melanoma is because microscopic cells may remain even after removing the entire tumor in layers. In addition, melanoma cancer can be difficult for the surgeon to detect microscopic melanoma cells that could spread throughout the body.

Which Is Best for Me?

While you may be tempted to choose the procedure that promises a higher cure rate and reduced chance of recurrence, it is essential to consult an experienced dermatologist when selecting the right option. MOHS surgery vs excision is not that easy to decide for yourself. The best treatment option for you will depend on the size of the tumor, its location, and the type of skin cancer. The doctor will also evaluate the risks associated with each procedure and your overall health.

Your dermatologist can guide you on which option is best for you and explain why one may be preferred. Ultimately, choosing the safest and most effective technique for removing skin cancer while preserving as much normal tissue as possible is essential.

MOHS vs Excision
Cropped shot of an attractive woman admiring her face in the bathroom mirror

Mohs Surgery vs Excision: Conclusion 

We hope you now have a better grasp of MOHS surgery vs excision. Mohs surgery has been a valuable tool for dermatologists to treat skin cancer effectively. This minimally invasive procedure can remove tumors from delicate areas with minimal damage to healthy tissues. While some discomfort may be expected after the procedure, proper care of the wound site can help alleviate any pain or discomfort. Keeping the wound clean, dry, and protected from infection is vital for successful recovery. It’s also important to know when to seek medical support in case of complications after the procedure. 

At BHSkin Dermatology, we strive to provide our patients with the highest quality of care. Our Board-certified dermatologists are experts in MOHs surgery and all aspects of skin cancer treatment. We use advanced technology and techniques, such as MOHs surgery, to ensure you get the best possible outcome. Contact us today to schedule an appointment or learn more about our services.


Author: Don Mehrabi

Dr. Don Mehrabi is a board-certified dermatologist providing medical care to patients in the Beverly Hills, California area at BH Skin Dermatology.

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