Mohs Reconstruction FAQ’s
After a Mohs procedure is completed, there is a defect left in the area where the tumor was. This defect may be small or very large and it may be in a non cosmetic/functional area or it might be in a critical area such as the nose, eyelid, cheek, forehead or ear. Mohs reconstruction is the process of repairing such defects to restore function and/or aesthetics. Who will perform the reconstruction and what type of reconstruction is required depends on where and how large the defect is.
If a small skin cancer is removed using Mohs surgery and the resulting defect is small, it may be allowed to heal on its own much like when a person scrapes their elbows or knees. If the defect is too large or in a location which is not amenable to healing on its own, then a reconstructive technique needs to be used in order to provide the best aesthetic and functional result. There are several types of reconstructive techniques depending on the size and location of the defect. Please see the “Types of reconstructive procedures” section below for more details.
Mohs reconstruction may be performed by the dermatologist performing the Mohs procedure or the patient may be referred to a Plastic and Reconstructive Surgeon or specialized ENT surgeons trained to perform such reconstructive procedures. Which type of specialist closes the procedure will depend on the size of the defect, the location of the defect, and the preference of the Mohs surgeon.
The term “Mohs” or “Mohs procedure” is actually an abbreviation for the official name of the procedure, Mohs Micrographic surgery. This procedure is named after Dr. Frederic E. Mohs (1910-2001) the inventor of the procedure. Mohs reconstruction is a separate procedure which is performed to repair the defect left after a Mohs procedure has been performed.
For a detailed history of Dr. Mohs’ life visit the following websites:
– American College of Mohs Surgery https://www.mohscollege.org/
– Skin Cancer Foundation https://www.skincancer.org/
Depending on the size and location of the defect, the dermatologist performing the Mohs procedure may allow the area to heal without closure or may perform one of the various reconstructive procedures available to repair the area. The dermatologist may also choose to refer the patient to a Plastic & Reconstructive Surgeon or ENT surgeon for reconstruction of the defect after the procedure is completed.
There are various types of reconstructive procedures that may be utilized to reconstruct the defect left after a Mohs procedure. The procedure used will depend on the size and location of the defect as well as the preference of the patient and doctor performing the reconstruction. See the various reconstructive procedures in the section below labeled “Surgical Procedures Used in Mohs Reconstruction”
Reconstruction of the defect that is left after Mohs surgery may be repaired by various methods. The choice will depend on the size and location of the defect as well as the preference of the Mohs surgeon and the patient. The Mohs surgeon may choose to allow the area to heal on its own without repair if it is small enough, or they may decide to perform one of the various reconstructive techniques described below in the section labeled “Surgical Procedures Used in Mohs Reconstruction”. The Mohs surgeon may also refer the patient to a Plastic and Reconstructive Surgeon or ENT surgeon after the procedure for repair of the defect. In this case, the patient may meet with the Plastic and Reconstructive Surgeon or ENT surgeon prior to the Mohs procedure for a consultation or may have an initial consultation after the Mohs procedure has been completed.
Depending on the size and location of the Mohs defect, the planned reconstructive procedure, and the medical history of the patient, the reconstruction may be performed with local anesthesia or may be need to be performed with conscious sedation (twilight or light anesthesia) or general anesthesia. These options will be discussed with the patient prior to the procedure. The patient and reconstructive surgeon can decide the best option at that time.
Certain Mohs reconstructive procedures can be performed in the office with local anesthesia, however, larger and more complex procedures may need to be performed in a surgical center with conscious sedation (twilight) or general anesthesia.
The answer to this question is still debatable. The traditional answer is that it should be repaired soon after the Mohs procedure, ideally within 48 hours to avoid an increase in the chances of complications. However, there was a recent article published in JAMA Facial Plastic Surgery by Matthew Q. Miller, MD (https://jamanetwork.com/journals/jamafacialplasticsurgery) in which a retrospective, single-institution cohort study from January 2012 through March 2017 was performed to evaluate this question. The study evaluated A total of 633 defects in 591 patients and found that delaying reconstructive surgery more than 2 days after MMS was not associated with an increased risk of complications. Please refer to the article here (https://jamanetwork.com/journals/jamafacialplasticsurgery/fullarticle/2653281) for details of the study and its conclusions.
If the area is not repaired it is left to heal by secondary intention. During this process, the body will fill in the area with tissue, healing the defect from the bottom up without repair by the surgeon. This process will not be recommended for large and complex defects or defects in particular areas of functional or cosmetic concern. When allowed to heal by secondary intention, the process may take up to 4-6 weeks or more to heal.
Mohs surgery is a procedure developed by Frederic Edward Mohs in 1933. It is designed to remove skin cancers with precisoin while sparing the most amount of normal tissue possible. The procedure is commonly used to remove the two most common skin cancers, squamous cell carcinoma and basal cell carcinoma, in areas where precision and/or tissue sparing are of concern. Please see FAQ’s below for detailed descriptions of Mohs surgery for Squamous Cell Carcinoma and Basal Cell Carcinoma.
Basal Cell Carcinoma (BCC) is the most common type of skin cancer. BCC usually develops on sun-exposed areas of the skin, especially on the head and neck. Basal cell carcinomas tend to grow slowly and rarely spread to other parts of the body. However, if left alone, they can spread locally invading local bone, tissues, and other structures causing damage in these areas.
Basal cell carcinomas arise from cells within the basal layer of the epidermis. The basal layer is the deepest layer of the epidermis and gives rise to the name Basal Cell Carcinoma. A mutation of the DNA of a cell in the basal layer causes the cell to multiply and grow in an unregulated fashion. This growth, left untreated, results in an tumor of the skin. Mohs surgery is considered the most effective technique for treating basal cell carcinomas with the following success rates as described by the Skin Cancer Foundation: Up to 99% for a skin cancer that has not been treated before and up to 94% for a skin cancer that has recurred after previous treatment.
Squamous cell carcinoma (SCC) is the second most common type of skin cancer after Basal cell carcinoma. Squamous cell carcinoma arises from cells in more superficial layers of the skin than the basal cells are found. These cells are called squamous cells, thus giving rise to the name squamous cell carcinoma.
Squamous cell carcinomas, like basal cell carcinomas, tend to appear on sun-exposed areas of the body such as the face, ears, neck, lips, and back of the hands. SCC also may develop in chronically irritated areas of skin, scars, sores, etc. SCC includes a variant referred to as keratoacanthomas which have unpredictable growth patterns and are treated as SCC.
Although SCCs typically remain localized to the area in which they present, they are more likely than Basal Cell carcinomas to spread to other parts of the body.
Mohs surgery is considered the most effective technique for treating squamous cell carcinoma with the following success rates as described by the Skin Cancer Foundation:
Up to 99% for a skin cancer that has not been treated before and up to 94% for a skin cancer that has recurred.
Surgical Procedures Used in Mohs Reconstruction
When the defect is small or in a non critical aesthetic/functional area closure by primary or secondary reconstruction is possible
If the area is small enough and in an appropriate location, it may be left alone to heal “naturally”. The term for this is healing by “secondary intention” (Primary intention is when the tissue edges are brought together and there is no defect to fill in). The body will fill in the defect by itself with tissue similar to what it does for a scrape or abrasion. If performed under the correct circumstances this technique will result in a good cosmetic result. If it is used under incorrect circumstances the area may have significant scarring and retraction and an unaesthetic appearance.
If the tissue edges of the defect can be re-approximated by performing local undermining of the tissues to mobilize them then they can be “closed primarily” referred to as healing by “primary intention”. This is the way in which most lacerations and surgical incisions are closed. The edges may be held in position with sutures (stitches), skin glue, staples, or surgical bandages. If the tissues are well re-approximated and not under tension when closed, this technique can have a good cosmetic result.
Medium Sized Defects
Depending on the size and location of the defect and the preference of the surgeon and patient, skin grafting may be a reconstructive option. It is a less complicated procedure than the tissue flaps discussed below but may have a less cosmetic result. Skin grafting involves removing either a split thickness layer of skin or a full thickness layer of skin from a donor site on the body, typically the thigh or buttocks. This skin graft is then prepared, laid in place over the defect, sutured in position, and a pressure dressing is applied. This grafted skin will then integrate with the underlying tissues and eventually heal on top of the wound providing a skin covering.
Local Tissue Flaps (Adjacent Tissue Rearrangement)
These techniques utilize geometry to rearrange local tissues allowing tissues to stretch from one area to cover another area. If performed correctly, the rearrangement allows the wound to be closed without tension and without transferring skin from another location. The most common example of an adjacent tissue rearrangement is Z-plasty procedure.
Local tissue flaps are created using tissues adjacent to the defect. The tissue flap is created using knowledge of geometry in order to rotate the tissue into the defect while allowing for closure of the donor site (where the flap was removed from) as well as knowledge of anatomy making sure to include the proper blood vessels to allow the flap to survive in its new position. Local tissue flaps include flaps which pivot around point at the base of the flap to reach the defect referred to as pivotal flaps as well as flaps which advance to fill the defect referred to as advancement flaps.
V-Y and Y-V flaps
Both of these flaps are developed by creating a v shaped flap. The flap can then be advanced by recoil or by being pulled forward. If the V shape is allowed to recoil it will result in a Y shape. This is referred to as a V-Y advancement. If the V shape is to be advanced forward a straight line incision will be made in front of the V, this will result in a V shape when completed. This is therefore referred to as a Y-V advancement.
Unipedicle Advancement Flap
Unipedicle advancement flaps are developed directly adjacent to the defect and advanced directly into the defect. These can be developed on both sides of the defect. This is referred to as a bilateral unipedicle advancement flap.
Rotation flaps are best used to close triangular defects. They are designed directly adjacent to the defect and rotated to repair the area.
Transposition flaps are designed to transpose tissue adjacent to the defect into the defect. The donor site is then closed or allowed to heal by secondary intention. Transposition flaps are very common flaps used to repair small to medium sized defects in the head and neck. The two most common transposition flaps are the rhomboid flap and the bilobed flap
Interpolated flaps are similar to transpositional flaps in that they pivot around a point at the base of the flap, however in contrast to a transpositional flap an interpolated flap is not directly adjacent to the defect. The flap therefore has to pass over or under intervening tissue. If the flap passes under the tissue through a tunnel it may be left to stay permanently. If the flap passes over the intervening tissue than after the flap heals in the defect, the flap will need to be divided. An interpolated flap passing over tissue will require a two-stage procedure. The first procedure is developing the flap and inserting it into the defect. The second stage is dividing the flap and removing or repositioning the portion that is on top of the intervening skin. The classic interpolated flap in facial reconstruction is the forehead flap used to repair nasal defects
Island flaps are developed as a free island of tissue that is attached only by a pedicle of soft tissue or just an artery and vein. The island can then be transferred to an adjacent area. The distance the island can move is dependent on the length of the pedicle.
Advanced Reconstruction Techniques for Larger Defects
When the defect is too large or no amenable to natural healing, primary closure, or adjacent tissue rearrangement, more advanced soft tissue reconstruction techniques need to be applied.
Free Flap Tissue Transfer For Major Reconstruction After Mohs
Free flaps are tissue flaps with an attached artery and vein that are completely removed from a donor site and transferred to a recipient site (defect). The artery and vein of the “free flap” are anastomosed to an artery and vein in the area of the defect to bring blood supply to the flap. These flaps are the most complicated flaps, and they are rarely used for Mohs reconstruction.