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Mohs surgery is a highly specialized technique for the treatment of skin cancer. It offers the highest reported cure rate and potential for recovery of any skin cancer treatment - even if the skin cancer has been previously treated. It is named after Dr. Frederic E. Mohs who pioneered the technique in the 1930's at the University of Wisconsin. Since then, the procedure has been refined and perfected and has gained international recognition and acceptance over the last twenty years.

Mohs surgery differs from other skin cancer treatments in that it permits the immediate and complete microscopic examination of the removed cancerous tissue so that no invisible extensions of the cancer are left behind.

Mohs surgery relies on meticulous mapping and preparation of the removed cancerous tissue in coordination with the precision and accuracy of a microscope which is used to map out the microscopic roots of the tumor which are not visible to the naked eye. This is an advantage in treating skin cancers that can be deceptively large (more extensive under the skin than they appear to be from the surface). These cancers can have microscopic extensions in the skin, and also along nerves, blood vessels and cartilage. Skin cancers that have recurred after previous treatments may send out deep extensions under the scar tissue that resulted from previous procedures. Mohs surgery is specifically designed to remove these cancers by tracking and removing these cancerous "roots." This provides the highest cure rate and the greatest conservation of normal healthy tissue and skin.

Mohs surgery:

  • Offers the highest cure rate
  • Offers the lowest chance for regrowth
  • Minimizes potential for scarring and disfigurement
  • Offers the most exact and precise method of removal


The actual Mohs process itself includes a specific sequence of surgery and pathological inspection. It is performed in our office utilizing local anesthesia and sterile technique. Although you are awake for the entire procedure, discomfort is minimal and usually no greater than that experienced at the time of your biopsy. After the area is completely numb, the procedure is as follows:
  1. The obvious tumor is removed by scraping (curettage).
  2. A thin layer of additional tissue is then taken around and under this area.
  3. A temporary bandage is then placed over the wound.
  4. The removed tissue is taken to our lab, cut into sections, stained and marked on a detailed diagram (Mohs map), which is used as a guide in order to map out the precise location of any remaining cancer cells.
  5. The tissue is then frozen in a cryostat, and the histotechnician cuts thin slices from the undersurface and edges of the specimen with a special blade (microtome) and places them on a glass slide for microscopic examination. This is the most time consuming portion of the procedure, often requiring one hour or more to complete.
  6. Your doctor then carefully examines the tissue under the microscope.
  7. If any residual cancer is found, it is carefully marked on the Mohs map and an additional thin layer of tissue is removed from the involved area (Stage II). This tissue undergoes the same processing and evaluation as above.
  8. When microscopic examination reveals that there is no remaining cancer in the surgical site, the surgical defect is then ready for repair (reconstruction).


The best method of repairing a wound resulting from Mohs surgery is determined after the cancer is completely removed. Dr. Nelson will usually give you some idea of what they think will be most likely at the time of your initial pre-operative visit. Some reconstructive options are:
  • Natural healing (granulation) - for small wounds and/or wounds in certain locations
  • Stitches (primary side-to-side closure)
  • Skin graft - movement of healthy skin from another location to cover the wound
  • Skin flap - movement of nearby adjacent skin to cover the wound
  • Reconstruction by a physician who specializes in complicated surgical repairs. If you have been referred to us by a physician skilled in skin closures (for example a plastic, oculoplastic, head and neck, or other type of reconstructive surgeon), he or she may perform the final reconstruction after your skin cancer has been removed by Mohs surgery.

In Summary

Mohs surgery allows the Mohs surgeon to use the microscope to guide in the removal of the skin cancer resulting in the highest cure rate, while preserving as much normal, healthy tissue as possible. There will be a scar following the surgery, as with any surgery, although every attempt is made to minimize it.
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