Mohs’s Micrographic Surgery
Mohs?surgery is a microscopically controlled technique that may be used for all types and sizes of BCCs. The procedure is unnecessarily destructive for smaller lesions or for lesions with well-defined clinical margins, such as nodular or superficial multicentric BCCs. Mohs?surgery is the treatment of choice for most sclerosing BCCs and other BCCs with poorly defined clinical margins; for tumors in areas of potentially high recurrence, such as the nose or eyelid; for very large primary tumors; and for large recurrent BCCs.
The clinically apparent area is removed with a curet. A thin, horizontal layer of tissue is removed with a scalpel and divided into more convenient smaller specimens for frozen section. Two adjacent edges of tissue are dyed red and blue to provide spatial orientation. A diagram of the section is prepared, and the number and color coding is indicated on the map. Specimens are mounted in a cryostat and then sectioned. Cut sections are stained and microscopically examined. The location of the tumor cells is indicated on a map and the above steps are repeated only in areas with tumor until a cancer-free plane is reached.
The defect created by the modern fresh tissue technique can heal by secondary intention or can be closed. The advantages of the microscopically controlled technique are that it preserves maximum amounts of normal tissue around the cancer, and it provides great reliability in determining adequate margins of excision. The disadvantage is that it is time-consuming, requiring hours or sometimes days to perform.