What is Mohs Micrographic surgery (Mohs)? It is a specialized, highly effective technique for the removal of skin cancer. The procedure was developed in the 1930s by Dr. Frederic Mohs at the University of Wisconsin and is now practiced throughout the world. 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 all the "roots" and extensions of the cancer can be eliminated. Due to the methodical manner in which tissue is removed and examined, Mohs surgery has been recognized as the skin cancer treatment with the highest reported cure rate.
When is Mohs surgery performed? Mohs micrographic surgery is used for skin cancers that have recurred following previous treatment or for cancers that are at high risk for recurrence. Mohs surgery is also indicated for cancers located in areas such as the nose, ears, eyelids, lip, hairline, hands, feet, and genitals, in which maximal preservation of healthy tissue is critical for cosmetic or functional purposes.
What is the procedure for Mohs? The surgery is performed as an outpatient procedure in our office. The patient is awake during the entire procedure, but discomfort is usually minimal and no greater than it would be for more routine skin cancer surgeries. The Mohs procedure is illustrated in the following diagrams.
Step 1: The area to be treated is cleansed, marked, and injected with a local anesthetic. The Mohs surgeon removes the visible cancer, along with a thin layer of additional tissue (Stage I). The tissue is processed and examined (this typically takes 45 min to 1 hour)
Step 2: The removed tissue specimen is cut into sections, stained, and marked on a detailed diagram (Mohs Map)
Step 3: Tissue is frozen on a cryostat and technician removes very thin slices from the entire edge and undersurface. These slices are then placed on slides and stained for examination under the microscope.
Step 4 : The Mohs surgeon carefully examines the entire undersurface and complete edge of the specimen and all microscopic "roots" of the cancer are precisely identified and pinpointed on the Mohs map. Upon examination, if residual cancer is found, the Mohs surgeon utilizes the Mohs map to direct the removal of additional tissue (Stage II). Note that additional tissue is removed only where cancer is present.
Step 5: This process is repeated as many times as necessary to locate any remaining cancerous areas within the tissue specimen. Once microscopic examination reveals that there is no remaining tumor, the surgical defect is ready for repair (stitches)
Our Mohs Lab: