Mohs micrographic surgery is a specialized form of skin cancer excision in which one physician functions as surgeon and pathologist, verifying surgical margins intraoperatively in successive stages.
Mohs surgery achieves the highest cure rate and is the treatment of choice for basal cell and squamous cell carcinoma with high risk of recurrence or progression and for tumors in anatomic areas where tissue sparing is critical.
Mohs surgery may also be used for treatment of melanoma in situ and other skin cancers in which pathologic margins can be verified on frozen sections.
Mohs surgery optimizes functional and cosmetic outcomes after skin cancer removal, has a low rate of postoperative complications, and is highly cost-effective for appropriately selected tumors.
INTRODUCTION AND BACKGROUND
Complete surgical removal is the cornerstone of therapy for solid tumors. This is particularly true for nonmelanoma skin cancers, which have a low risk of metastasis. Complete surgical removal may be difficult to achieve, however, for skin cancers with extensive subclinical spread and for lesions adjacent to vital structures such as the eye. Staged excision or intraoperative pathologic examination of margin status have been used to help ensure adequate surgical margins, but these techniques are limited by logistical hurdles in coordination and communication between the surgeon and pathologist, the inability to precisely map areas of positive margins in three dimensional space, and the inherent limitation of standard pathologic specimen processing, which only examines a small, noncontiguous fraction of the surgical margin. In the 1930s and 1940s, Dr. Frederic Mohs developed a novel method of skin cancer excision using zinc chloride paste to chemically fix the tissue in situ on the patient followed by staged excision with rapid pathologic examination of the surgical margins by the operating physician.1 The procedure was originally named chemosurgery because of the use of a chemical fixative (chemotherapy was not used). In his seminal report, Dr. Mohs reported an overall cure rate of 93% in 425 cases of nonmelanoma skin cancer, many of which were advanced lesions not amenable to standard surgical excision.
In the 1970s and 1980s, the use of chemical fixative was gradually replaced with frozen section analysis of unfixed (fresh) tissue, which allowed the procedure to be completed in hours rather than days. Application of the technique grew rapidly in subsequent years, as the superiority of the procedure over other forms of treatment was established in the peer-reviewed medical literature. Today, the technique known as Mohs micrographic surgery (MMS) is used for treatment of approximately one in five skin cancers in the United States.2 It is the standard of care for basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) with a high risk of recurrence or in sensitive anatomic locations or where clinical margins are difficult to ascertain. It is routinely indicated for treatment of other cutaneous malignancy as well. The inherent advantages of complete microscopic surgical margin analysis ...