Once fixed to the block, the tissue is engulfed in appropriate embedding medium and placed within the cryostat. The block is slowly cut to produce several micron-thin wafers of tissue that are then mounted on glass slides and processed with hematoxylin and eosin (H&E) or various stains. The first wafers of tissue that come from the tissue block are those that are closest to the margin that was excised. Thus, 100% of the epidermis and deep margin can be visualized. “Deeper sections” are those that come from deeper cuts within the tissue and are more likely to show the malignant neoplasm.
The evaluation of immediate margins at the very edge of the tissue is in contrast to the technique of “bread-loafing,” which is the standard of evaluating margins after a WLE.11 With this process, the pathologist examines sections that are cut 2- to 4-mm apart. This process only allows the pathologist to examine roughly 1% of the total tissue that was excised, and large variability in cutaneous representation can occur depending on the individual who cuts and processes the tissue.11
Closing the defect
Once the site is deemed clear of residual tumor, the Mohs surgeon approaches the defect and determines the most appropriate way to close the surgical wound. Mohs surgeons are trained to close wounds using a variety of methods, including complex linear closures, flaps, and full-thickness skin grafts. Thoughtful consideration of local anatomy, cosmetic landmarks that may be affected by the closure method, and local tissue laxity are evaluated.
Depending on the location, a secondary intention closure may prove to be just as effective and cosmetically satisfying as a primary intention closure. In light of the many methods of closure, a complex or large surface area defect may better be suited for evaluation and closure by another specialist such as an ENT physician, ophthalmologist, or plastic surgeon.12
Lower recurrence rates for patients who undergo Mohs surgery
As noted earlier, the cutaneous malignancies most commonly treated with MMS are BCCs, followed by SCCs.13 Comparison studies between WLE and MMS show clinically significant differences in terms of recurrence rates between the 2 procedures.
Continue to: For BCCs