Initially, when Dr. Mohs introduced his procedure it was not as refined as it is today. The initial procedure involved the dermatologist removing a thin layer of affected skin from the affected area, dressing it with a zinc chloride paste to allow it heal for a few days, then asking the patient to come back in a few days, after the skin had time to heal from the surgery, for re-evaluation. At this point the patient would have one more layer of skin removed for analysis, the affected area would be redressed with the zinc chloride paste, and if the test results showed any more cancer cells on the edge of the skin the whole procedure would be repeated. In this way, the process could take days or weeks.
This first model of Mohs surgery was met with scrutiny from the medical community, and dubbed controversial. The reason for this are partly because until that time dermatologists had never performed surgical operations. However, the other problem with it was that the zinc chloride paste used to treat the skin in between surgeries caused a great deal of pain and discomfort among patients.
A couple decades later in the 1950s, a new variation of Mohs surgery started to become popular: rather than removing a layer of tissue, dressing the area with the zinc chloride paste, then asking the patient to come back for re-examination, the doctor would use local anesthesia on the affected area, then simply remove one thin layer of tissue at a time, examining each layer right away to see if the edges had cancer cells. This process would be repeated until there was no more cancer cells upon examination.
Today, Mohs surgery has the highest cure rate for certain types of skin cancer. It is a procedure that is used on large skin lesions, rapidly growing lesions, and cancer lesions with poorly defined borders. This procedure helps preserve as much healthy skin on the patient as possible. This is especially useful if the cancer is on a sensitive area such as the hands, feet, or face.