More About Mohs Surgery
by Raymond Dufresne, Jr., MD
Fresh Tissue Technique
Mohs micrographic surgery has represented a major advance in the treatment of cutaneous carcinoma since its development in the 1930's by Fredrick Mohs, MD. This technique; now commonly referred to as Mohs surgery, included application of the zinc chloride fixative, sequential excision of tumor, detailing marking and mapping of the removed tissues, and horizontal sectioning of the excised material with complete margin control. Mohs initially used the "fresh technique" in 1953 when he excluded the fixative in the treatment of an eyelid tumor but continued the other essential elements of Mohs surgery. The fresh tissue variant, popularized by Theodore Tromovitch, MD, proved to have the same high cure rates as the original fixed tissue technique.
The fresh technique afforded several advantages over the original chemosurgical technique. The time delay required for tissue fixation with the zinc chloride paste was avoided; the use of local anesthesia resulted in a relative painless procedure; and the elimination of the fixative avoided the local tissue irritation and the possibility of overpenetration by the zinc chloride fixative. Also, immediate reconstruction of the defect became technically possible and the interdisciplinary approaches more feasible. Because of these factors, the fresh technique has enjoyed great popularity, although the fixed technique is still useful to treat certain vascular tumors or tumors in vascular sites, very large or deeply invasive tumors and tumors invading bone.
Operative Technique
Preoperative Evaluation
A general history taking and physical examination are performed to ascertain the medical status of the patient. Allergies, medications, bleeding tendencies, healing abnormalities and cardiovascular and neurologic status should be noted. Pertinent information such as the duration of the lesion, previous treatment, and risk factors of petrochemical, arsenic, radiation, and ultra-violet exposure should be obtained. The site and size of the lesion, regional nerve function, and the presence or absence of adenopathy should also be noted. This evaluation may also suggest the need for additional laboratory tests, electrocardiography, magnetic resonance imaging (MRI) or x-ray studies and possible consultation with other specialists. During the preoperative evaluation, the etiology, natural history, and prognosis of the skin cancer, details of Mohs surgery, possible plans for reconstruction, the risks and complications of the procedure and alternative forms of treatment are always discussed.
Procedure
The surgery is usually performed in an outpatient suite or office setting. General anesthesia and a full operating suite are typically required only for exceptional cases. This outpatient approach involves minimal alteration of patients' daily routine, including use of medications, and results in a very safe procedure that can be performed with low morbidity and very low mortality risks. Although patient restrictions are minimal, aspirin should be avoided for two to four weeks and alcohol for a few days preoperatively to reduce the risk of bleeding. In most instances, patients can continue normal use of routine medicines, and preoperative fasting is not a requirement. Family members are encouraged to accompany patients and bring whatever may help them to relax and be comfortable. Properly prepared patients in a relaxed environment usually tolerate the procedure quite well.