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Mohs Micrographic Surgery at a Glance
  • Mohs micrographic surgery (MMS) is a precise method of treating skin cancer that results in the highest cure rate with maximal tissue conservation, cosmesis, and function.
  • MMS is indicated for the treatment or basal cell cancer and squamous cell cancer and certain less common skin cancers.
  • Specific indications for MMS include location in high-risk anatomic sites, aggressive histology, recurrent tumor, and when there is a need for maximal preservation of tissue.
  • Advances in processing and staining techniques and the use of immunostains have increased the speed and accuracy of MMS as a cost-effective means of skin cancer extirpation.

Mohs micrographic surgery (MMS) is a surgical technique developed to excise skin cancer under complete microscopic control. The fresh frozen tissue technique is used, which permits immediate examination of the specimen, and the tissue is oriented in a way to permit evaluation of all surgical margins. This is distinct from the traditional bread loafing technique used to process tissue specimens. A special orientation is combined with a precise mapping technique, which leads to maximal conservation of normal tissue. The technique was developed by Dr. Frederick Mohs approximately 80 years ago using a fixed tissue technique that relied on zinc chloride paste. The original term, chemosurgery refers to the use of the tissue fixative which is no longer used. As a result, the term chemosurgery is considered archaic.1 MMS has been described by various names such as chemosurgery, microscopically controlled excision, and microscopically oriented histographic surgery. The latter is an attempt at creating an acronym to replace the eponymous term Mohs.

In the past several decades, the mapping component has been retained but the procedure has been refined using frozen tissue rather than fixed tissue, which has permitted more efficient patient care. The advantages of MMS over conventional excisional surgery include maximum cure rate and optimal preservation of healthy tissue. The latter serves to enhance cosmetic outcome and preserve function where applicable. MMS is now recognized as the standard of care for the treatment of various skin cancers in indicated circumstances. The most common cancers treated by this method are basal cell carcinoma (BCC, 73%) and squamous cell carcinoma (SCC, 23%).2 A defining characteristic of MMS is that the surgeon acts to interpret the histopathologic specimens. Specifically, the MMS procedure requires a single physician to act in two integrated but separate distinct capacities as surgeon and pathologist. MMS is a highly technical procedure that requires meticulous attention to detail and considerable training and experience to achieve the expected high cure rates.

Mohs surgery is performed under local anesthesia in the office setting or in an ambulatory center. In unusual cases, where multiple cancers or complex malignancies are to be removed, sedation may be used.3 Prior to surgery, it is essential to have the patient affirmatively identify the biopsy site as very often the biopsy site may fade due ...

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