The Mohs surgery technique combines the surgical removal of cancer with immediate microscopic examination of the removed tissue to identify cancerous areas. Mohs surgery not only has the highest cure rate of all treatment methods, but it creates the smallest possible surgical defect, allowing for the best cosmetic results (less scarring).

Mohs Micrographic Surgery Advantages

  1. Mohs micrographic surgery offers the highest potential cure rate for removal of skin cancer:
    • 95% for recurrent tumors
    • 99% for primary tumors

    This high cure rate is related to horizontal sections taken from the bottom and sides of each tissue block examining 100% of tissue margins.

  2. Healthy tissue is spared leading to smaller scars as repairs are less complicated.
  3. The complete removal of the skin cancer and reconstruction, when indicated, can often be completed in a single day, as the procedure is performed in Dr. Donnelly’s office and pathological examinations are conducted immediately.
  4. Unless otherwise indicated, the procedure is performed under local anesthesia, thus eliminating the risks of intravenous sedation or general anesthesia.
  5. Mohs micrographic surgery is cost-effective. The procedure is comparable to the cost of electrodesiccation and curettage, cryosurgery, and office excision.

Mohs micrographic surgery, an advanced treatment for skin cancer, offers the highest potential for cure – even if the skin cancer has been previously treated. This procedure is a state-of-the-art treatment in which the physician serves as surgeon, pathologist, and reconstructive surgeon. It relies on the accuracy of a microscope to trace and ensure the removal of skin cancer down to its roots. This procedure allows dermatologists trained in Mohs surgery, to see beyond the visible disease by precisely identifying and removing the entire tumor, leaving the healthy tissue intact and unharmed. Mohs surgery is most often used in treating two of the most commons forms of skin cancer – basal cell and squamous cell carcinoma.

Clinical studies have shown that the cure rate for Mohs Micrographic Surgery is the highest of all treatments for skin cancer – up to 99 percent for primary cancer – and 95 percent for recurrent cancer. As the most exact and precise method of tumor removal, this procedure minimizes the chance of regrowth and lessens the potential for scarring and disfigurement. Therefore, Mohs surgery offers the highest potential for complete removal of cancer while sparing the surrounding healthy tissue.

Learn More About Mohs



Developed by Frederic E. Mohs, MD in the 1930’s, the Mohs micrographic surgical procedure has been refined and perfected for more than half a century. Initially, Dr. Mohs removed tumors with a chemo surgical technique. Over the course of a number of days, thin layers of tissue were excised and frozen before being pathologically examined. He developed a unique technique of color-coding excised specimens and creating a mapping process to accurately identify the location of remaining cancerous cells. As the process evolved, surgeons refined the technique and now excise the tumor, remove layers of tissue and examine the fresh tissue immediately. The normal treatment time has now been reduced to one visit and allows for the immediate reconstruction of the wound. The heart of the procedure – the color coded mapping of the excised specimens and their thorough microscopic examination – remains the definitive part of the Mohs micrographic surgery.


Mohs micrographic surgery, while used primarily to treat basal and squamous cell carcinoma, can also be used to treat less common tumors, including dermatofibrosarcoma protuberans. Mohs surgery is indicated when: 1) the cancer was treated previously and recurred, 2) scar tissue exists in the area of the cancer, 3) the cancer is in a difficult area where it is important to preserve healthy tissue for maximum functional and cosmetic result (ie – eyelids, nose, ear, lips), 4) the cancer is large, 5) the edges of the cancer cannot be clearly defined, or 6) the cancer grows rapidly or uncontrollably.


The best method of managing a wound resulting from surgery is determined after the cancer is completely removed. When the final defect is known, management is individualized to achieve the best results to preserve functional capabilities and maximize aesthetics. The Mohs surgeon is trained extensively in reconstructive procedures and usually will perform the reconstructive procedure necessary to repair the wound on the same day. A small wound may be allowed to heal on its own, or the wound may be closed with stitches, a skin graft or flap. In some cases, it is necessary to delay the repair to optimize the wound bed for the best surgical outcome or to allow time to optimize the conditions for a complex repair. If a defect is large enough to require sedation for the repair, another surgical specialist with unique skills may complete the reconstruction.

Cost Effectiveness

In addition to its high cure rate, Mohs micrographic surgery also has been shown to be cost effective. In a study of costs for various types of skin cancer removal, the Mohs process was found to be comparable to the cost of other procedures, such as electrodessication and curettage, cryosurgery and excision. It was found to be less costly than ambulatory surgery facility excision and radiation therapy.


The ability to perform the procedure in an outpatient office setting, the preservation of the maximum amount of normal skin (leading to smaller scars) and less complicated repairs involving fewer reconstructive procedures all make Mohs micrographic surgery the most efficient option. Additionally, the high cure rate minimizes the risk of recurrence and eliminates the costs of more comprehensive, serious surgery for recurrent cancers.

Treatment Issues

Common treatment procedures often prove ineffective because they rely on the human eye to determine the extent of the cancer. In an effort to preserve healthy tissue, too little tissue may be removed, resulting in recurrence of the cancer. If the surgeon is overcautious, more healthy tissue than necessary may be removed, causing excessive scarring and disfigurement. Some tumors do not respond as well to common treatments, including those greater than two centimeters in diameter, those in difficult locations and those complicated by previous treatment. Removing a recurrent skin cancer is more complicated because scar tissue makes it difficult to differentiate between cancerous and healthy tissue. In these cases Mohs surgery may often be the treatment of choice.

Emergency Information

In the event of an emergency outside of office hours, our on-call physician can be reached at 937-671-4000.

Mohs Micrographic Surgery Procedure

The Mohs process includes a specific sequence of surgery and pathological investigation. Mohs surgeons trace the paths of the tumor using two key tools:

  • map of the surgical sites
  • a microscope

The obvious tumor is removed with a scalpel. Mohs surgeons:

  • microscopically examine 100% of the skin margins of removed tissue to check for the evidence of cancer cells
  • create a map of the removed tissue to be used as a guide to the precise location of any remaining cancer cells

If any of the sections contain cancer cells, Mohs surgeons:

  • remove another thin layer of the tissue only from the specific area indicated by the map where cancer cells were detected
  • microscopically examine the newly removed tissue for additional cancer cells

If microscopic analysis still shows evidence of disease, the process continues, layer-by-layer, until the cancer is completely removed.