Originally developed in the 1930s, Mohs micrographic surgery has been refined into the most advanced, precise, and effective treatment for an increasing variety of skin cancer types. It was named after the physician, Frederic H. Mohs, MD, who pioneered the procedure. Mohs surgery is a specialized technique in which the skin cancer is removed in stages, one tissue layer at a time, preserving as much normal tissue as possible.

Advantages of Mohs Surgery

Mohs surgery has the highest cure rate for non-melanoma skin cancers (basal cell and squamous cell cancers). This unique procedure is particularly effective because of the way the removed tissue is microscopically examined, evaluating 100% of the surgical margin. The pathologic interpretation of the tissue margins is done on-site by the Mohs surgeon, who is specifically trained in the interpretation of these slides and is best able to correlate any microscopic findings with the surgical site on the patient.


Minimizing the amount of healthy tissue lost


Maximizing the functional and cosmetic outcome resulting from surgery


In most cases, repairing the site of the cancer the same day the cancer is removed


The cure rate for Mohs surgery is the highest of all skin cancer treatments (up to 99% even after other forms of treatment have failed)


Mohs surgery is an extremely effective, intricate procedure that requires time and patience. It is helpful to become familiar with the process prior to your appointment. Mohs surgery is an outpatient procedure performed under local anesthesia. You will be awake for the entire procedure. It is done in a series of one or more layers called stages. After the area has been properly numbed and cleansed, the surgeon will remove the visible tumor along with a thin layer of surrounding tissue. The smallest amount of tissue that has a reasonable chance of curing the cancer is removed. Any bleeding is controlled with an electrical device called a Bovie, which will cauterize the tissue creating a pungent odor. At this point, the wound will be bandaged and you will have some waiting time.

Once the tissue is removed, a map is drawn which corresponds to the size, shape, and orientation of the tissue. The tissue is then taken to the lab which is located within the office. The histology technician inks and freezes the tissue, slices the tissue into sections, and then prepares the slide for staining. The way the technician slices the tissue is unique to Mohs surgery and ensures that the entire margin of the tissue is examined. Dr. Obadia then examines the slides and marks on the map any cancer that is present.

If cancer cells are found at any margin you will be brought back into the surgical procedure room so that another layer of tissue can be removed, processed, and examined in the above fashion. The map is used as a guide so that only tissue with residual cancer cells is removed. The process is repeated as many times as necessary to completely remove the tumor. Each stage may take one to two hours to remove, process, and examine. Therefore, your waiting time between stages will be about this long. Two or three stages are average. However, keep in mind that it may be more or may be less. Because of the uncertainty of the number of stages, plan to possibly be with us all day.

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Step 1

The skin cancer’s visible size and shape are determined. There may be tiny roots that can only be seen with a microscope. If these are not taken out, cancer will come back.

Step 2

The surgeon removes the tumor that can be seen.

Step 3

The surgeon removes a thin layer of skin from the wound and divides it into sections. Each is then dyed a certain color. Marks made on the skin show where the sample came from and its position. The surgeon draws a map to relate points on the tumor with the place where it used to be.

Step 4

The bottom and edges of the piece of cancerous skin are studied under a microscope. Wherever cancer cells still remain, a mark is made on the map. The surgeon removes another thin layer of skin at each mark and repeats these steps.

Step 5

When no more cancer cells are found in the wound or at its edges, the surgery is done. As much normal skin as possible is saved by this method. A smaller wound is more likely to heal with a scar that needs little or no repair.


  • Julia Obadiah, M.D.
  • Keleigh Nersasian, PA-C
Fax: 503.691.1144