Mohs surgery was developed by Dr. Mohs to microscopically remove all cancer. After the initial excision, the doctor reviews the microscopic elements of the tissue and determines if there's any residual cancer. If there's more cancer, then more tissue is removed. When there's no cancer noted, the defect may be confidently closed.
The procedure is often done in conjunction with a plastic surgeon or a facial plastic surgeon in order to be able to close the defect. Many times the cancer cannot be determined strictly by visually assessing the size of it and its removal may cause a large defect. Because of this, patients often feel that the Mohs procedure is actually a tissue destructive surgery.
My suggestion to you is find a qualified Mohs surgeon. Make sure that he or she is able to close a large defect or that they have a cooperative agreement with a facial plastic surgeon or a plastic surgeon. Very often small appearing cancers can create large defects so you don't want to be surprised when they happen!