What is MOHS' micrographic surgery?
MOHS' micrographic surgery is the most accurate form of skin cancer removal and provides the conserving of normal tissue more than any other method today. It is a time consuming, but very accurate, process for eliminating skin cancer. MOHS' micrographic surgery was used to treat skin cancers on both President Ronald Reagan and President George Bush. MOHS' micrographic surgery was developed by Dr. Frederick Mohs, a dermatologist and surgeon from the University of Wisconsin, over 50 years ago. This technique has been finely tuned to provide excellent results.

An example of the results of MOHS' micrographic surgery
Results after six-months are shown.

Fresh Tissue Technique
Mohs micrographic surgery is a highly specialized surgical technique that is commonly employed by specially trained physicians for the treatment of malignant neoplasms of the skin and mucosa. The Mohs technique couples high cure rates (highest of any treatment modality) with maximum normal tissue conservation by orienting the tissue in a way which allows for histologic evaluation of virtually 100 percent of the surgical margin.

It is an outpatient procedure done under local anesthesia (with or without mild sedation). The overall procedure is comprised of a series of excisions and pathologic tissue processing that are described as stages. All stages begin with establishing effective sedation and anesthesia. In Stage One, the clinically evident tumor is surgically debulked (removed). A beveled incision is made circumferentially around this defect to produce a uniformly thin (1-3 mm) saucer-like layer of tissue which is placed in a container in a way that meticulous orientation to the cutaneous defect can be maintained. A two-dimensional diagram, "the Mohs map," is drawn of the specimen, relating its orientation to the surgical defect. Following adequate hemostasis, the wound is dressed, and the patient is guided to a waiting area/recovery room while the tissue is processed. In the adjacent Mohs laboratory, the saucer-like specimen is subdivided, numbered and color-coded. These steps are recorded on the Mohs map. (Cutting smaller specimens allows the beveled edges of the specimen to fall into the same horizontal plane as the deeper tissues. Furthermore, because several sections of the smaller specimens fit onto a standard microscope slide, effectively adding a third dimension, interpretive accuracy is enhanced. These prepared specimens are handed to a specially trained histologic technician. While maintaining meticulous orientation of the specimens, the technician prepares horizontally oriented frozen sections. Each section is microscopically reviewed by the Mohs surgeon (who is trained in the interpretation of horizontally oriented pathology specimens).

In cases where microscopic examination reveals tumor in one or more of the subdivided specimens, a corresponding mark is drawn on the Mohs map. So marked, the Mohs map is used to precisely outline residual tumor within the surgical defect for subsequent Mohs stages. Subsequent stages are performed as outlined above while the surrounding normal tissues are spared.

The concept of orienting the tissue specimens horizontally, which allows for review of 100 percent of the surgical margin, is unique and is what sets Mohs micrographic surgery apart from all other skin cancer removal techniques. In addition, the Mohs surgeon performs the excision and interprets the pathologic specimens, further enhancing maintenance of appropriate orientation of tissues.

In contrast, all other excisional techniques rely on standard methods of tissue processing: a surgeon removes the tumor and passes it off to another physician, a pathologist. The pathologist then processes the tissue by one of several techniques, all of which orient the tissue specimens vertically. This has been shown to allow for surveillance of less than one percent of the surgical margins. For example, one commonly used technique removes samples from the tissue block that are analogous to slices from a loaf of bread. From these "slices," the pathologist must determine the status of the margins of the entire tissue block, but must do so without actually having the opportunity to review the entire surgical margin. Because the inherent risks of leaving residual tumor within the defect is greater with these standard techniques, surgeons must remove larger amounts of normal tissue to decrease chances of recurrence and spread of the tumor.