The Procedure


The Mohs Micrographic Surgery procedure relies on a specific sequence of surgery and pathological investigation:

  1. The surgeon identifies the visible skin cancer.
  2. The skin cancer and surrounding skin are anesthetized using local anesthesia, which is injected using a small needle.
  3. The visible skin cancer and a narrow margin of healthy-appearing skin are surgically removed with a scalpel and marked with reference points on the patient.
  4. An anatomic map of the removed tissue is created, which will guide the surgeon to the precise location of any residual cancer cells.
  5. The tissue specimens are labeled with dyes that allow the surgeon to reference the tissue seen on the microscope slides directly back to the specific location on the patient.
  6. The pathology technician processes the tissue specimens in the office lab and procedures frozen section slides.
  7. The slides are examined under a microscopic by the Mohs surgeon.
  8. If any of the microscopic sections contain tumor (i.e., skin cancer cells), the map guides the surgeon to the precise location where tumor roots remain.
  9. An additional layer of tissue is removed in the location of the roots, and the tissue is processed and examined as previously described.
  10. The tumor resection follows the same step-by-step process until all microscopic sections are clear from cancerous cells.
  11. At this time, the surgeon will discuss options for reconstructing the surgical defect with the patient.


STEP 1: The roots of a skin cancer may extend beyond the visible portion of the tumor. If these roots are not removed, the cancer will recur.

STEP 2: The visible portion of the tumor is surgically removed.

STEP 3: A layer of skin is then removed and divided into sections. The Mohs surgeon then color codes each of these sections with dyes and makes reference marks on the skin to show the source of these sections. A map of the surgical site is then drawn.

STEP 4: The undersurface and edge of each section are then microscopically examined for evidence of remaining cancer.

STEP 5: If cancer cells are found under the microscope, the surgeon marks their location onto the “map” and returns to the patient to remove another layer of skin – but only precisely where the cancer cells remain.

STEP 6: The removal process stops when there is no longer any evidence of cancer remaining in the surgical site. Because Mohs surgery removes only tissue containing cancer, it ensures that the healthy tissue is kept intact.