MOHs Micrographic Surgery Los Angeles | Dr. Ben Behnam

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MOHs Micrographic Surgery

MOHs Micrographic Surgery Los Angeles

Dr. Behnam is a member of the American Society for Mohs Surgery and was trained under the renowned and prominent Mohs surgeon Dr. Christopher Zachary. Mohs Micrographic Surgery is a tissue sparing procedure designed for removal of skin cancers, such as Basal Cell Carcinomas and Squamous Cell Carcinomas. Mohs Micrographic Surgery allows for complete examination of all surgical margins to ensure that margins are completely clear of tumor. It is typically indicated for skin cancers on the face, where tissue preservation is paramount.

It can also be employed for aggressive types of tumors, tumor size greater than 2 cm and recurrent skin cancers. There are four major steps, surgical removal of the skin cancer, preparation of the tissue for pathology reading by a technician using a cryostat, reading the pathology specimen under a microscope, and then surgical reconstruction of the defect. Mohs surgery allows for a cure rate of 97% to 99% for Basal Cell Carcinomas.

What is MOHS Micrographic Surgery?

MOHS micrographic surgery is a special form of surgical technique that uses pathological evaluation to remove skin cancers that are high-risk or located on cosmetically sensitive areas. In essence, it allows Mohs Surgeons like Dr. Behnam to be able to remove the skin cancer by examining the entire margin of the skin while simultaneously minimizing the amount tissue needed to be excised out.

The most important part of MOHS surgery is the method of preparing the tissue for histological evaluation that allows examination of 100% of the margins of the skin cancer. This combined with Dr. Behnam’s ability to produce a precise micrographic map of where the skin cancer is located and his ability to be both a surgeon as well a pathologist give him the unparalleled opportunity to have a high cure rate while providing tissue sparing ability for this type of surgery.

What are the indications for MOHS Micrographic Surgery?

Basal cell carcinoma and squamous cell carcinoma are examples of non-melanoma skin cancers, which are the most common types of cancers worldwide. They carry with themselves significant morbidity and occasionally mortality. There are many different methods of managing non-melanoma skin cancers, ranging from electrodesiccation & curettage (C&D), topical chemotherapy, regular surgical excision, radiation therapy, and Mohs surgery.

Mohs Micrographic Surgery allows examination of 100% of the tissue margins and has the highest cure rates of all forms of skin cancer surgeries. However it is not practical to use this technique for the management of every type of skin cancer, especially those that have lower risk of recurrence or in areas where sparing of tissue is not of paramount importance. Therefore, Mohs Micrographic surgery is very commonly used for skin cancers that are on cosmetically sensitive areas of the body such as the face, the hands and the feet where there is not much tissue to spare.


Also, MOHS is also indicated for skin cancers that are poorly differentiated or of higher metastatic risk. Finally, skin cancer that have perineural invasions or lesions that are greater than 2 cm in diameter or lesions that have very poorly-defined clinical borders are also candidates for Mohs Micrographic surgery.

How is MOHS surgery different from routine skin cancer excision?

Routine excision of skin cancers involves removing the skin cancer with 3 to 4 mm of margins. Once the tissue is removed, the specimen is send to an outside lab, where it is embedded in paraffin, slides are created and then is read by a dermatopathologist. This process is known as permanent sections. In this form, the dermatopathologist examines the peripheral margins of the specimen using what is known as a bread loaf technique. Bread loaf technique involves making thin cross sectional cuts along the tissue specimen.

These slices are representative of the tissue that was surgically removed. Several of these slices are read by the dermatopathologist, giving him the opportunity to detect if any of the outer or deeper margins of the specimen tissue are still involved with the skin cancer. However as you can imagine since several thin slices are examined by the dermatopathologist, this means that only a small portion of the total peripheral margin is specifically examined by this bread loaf technique. In fact only 0.01% of the surface area is examined using this method.

In contrast MOHS Micrographic surgery has a very unique tissue processing technique that allows 100% of the margin to be examined. This results in a much higher cure rate. Again, the key difference between traditional surgical excision and Mohs surgery is that with traditional surgical excision only 0.01% of the total margin is examined by the dermatopathologist whereas in the case of Mohs surgery 100% of the total margin is examined by the Mohs surgeon.

What is the cure rate for MOHS Micrographic Surgery?

The cure rate for MOHS Micrographic surgery is as high as 98% to 99%.

What is the history of MOHS Micrographic Surgery?

MOHs Micrographic Surgery Los AngelesMOHS surgery was pioneered by Dr. Frederick Mohs who first published this in 1941. His original technique involved the use of zinc chloride paste that was pasted on the cancerous tissue for 24 hours prior to surgical removal. When the skin cancer was excised, it was sectioned into several different pieces and the areas were marked with color dyes for orientation. The color dyes allowed for detailed mapping of the tumor indicating where the skin cancer might be located within the actual tissue.

Then physical pressure was applied to the tissue in order to flatten it so that all the lateral and deep margins will be present on the histological examination. Then several tissue sections were cut and then examined under microscope. If any skin cancer was observed, the exact location of the residual skin cancer was noted on the map using the dyes as orientation markers.

Over the next 30 years, the tissue processing for Mohs’ surgery has evolved from the zinc chloride paste to fresh frozen technique that was later described by Tromovitch and Stegman in 1974. The new fresh frozen technique, in contrast to the zinc chloride paste technique, is very important because it does not need zinc chloride paste, which leads to necrosis of the skin. It also allows dermatologist the opportunity to completely clear the skin cancer using multiple levels all in one day. The fresh tissue technique has become the standard of care in the MOHS micrographic surgery.

Steps in MOHS Micrographic Surgery:

  1. Excise the tumor
  2. Prepare the tissue
  3. Interpret the fresh frozen histological slides
  4. Creating the map of where the possible residual tumors might be
  5. Cut out the residual skin cancer and repeat this process until the entire tumor has been completely excised
  6. Close the surgical defect.

Mohs’ micrographic surgery requires the MOHS Micrographic surgeon to have an excellent understanding of both the cutaneous as well as the soft tissue anatomy, especially that of the face both for the excision of tumors as well as for reconstruction. One of the most important aspects of Mohs’ surgery is that the surgeon not only has to be able to excise the lesion but also serve as a pathologist to read the specimen during the surgery as well as having the capability of reconstructing the wound itself.

Are most skin cancers removed by MOHS surgery?

No. The majority of Basal cell and Squamous cell skin cancers in United States are treated by non-MOHS surgery techniques. These involved electrodesiccation & curettage, topical chemotherapy, regular surgical excision permanent sections as well as radiation therapy. These techniques provide reasonable cure rates that are also cost efficient. In contrast, MOHS micrographic surgery is designated only for high risk skin cancers or for skin Basal Cell and Squamous Cell carcinomas of the face, neck, hands and feet.

What are the treatment options for non-melanoma skin cancers?

Examples of non-melanoma skin cancers include Basal Cell Carcinomas and Squamous Cell Carcinomas. There are multiple treatment options for these types of skin cancers. These include electrodessication & curettage, cryotherapy (this was highly used mainly in the past and is currently not used as much), topical chemotherapy such has Aldara, Imiquimod, Efudex, and 5-fluorouracil cream. Finally the latest treatment management technique involves photodynamic therapy.

What are some of the key features for MOHS micrographic surgery?

  • 100% of the tissue margins are examined.
  • There is a very high cure rate.
  • This is a tissue sparing procedure.

A very precise map of where the residual tumor might exist can be produced.

Dermatologist is both trained in surgical excision of skin cancer as well as is trained as a pathologist to read the skin cancer during the same day and finally is trained to reconstruct the defect that has been created.

There are less side effects and complications because of the tissue sparing ability of MOHS surgery.

The cure rate is very high and leads to less recurrence of the skin cancer.

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