Mohs surgery - a new approach with a mould and glass discs: review of the literature and comparative study.

OBJECTIVE: Mohs surgery is a frozen section-guided surgical excision that is the treatment of choice for aggressive cutaneous malignancy. But it is labour intensive, particularly because numerous levels are needed on each specimen to obtain a complete histologic section. Three different techniques to Mohs surgery are compared. Our new approach with moulds and glass discs is explained and discussed.
DESIGN: Review of the literature and comparative study using skin specimens of fresh cadavers.
SETTING: Regional care centre.
METHOD: First, we evaluate, for each of the three different techniques, the number of 10 micron-thick frozen sections required to obtain a macroscopically complete cross section of the specimen. Second, we examine microscopically the quality of these first complete sections. Finally, once we have obtained a macroscopically complete cross section, we evaluate the number of deeper levels required to obtain an adequate microscopic section.
RESULTS: In the first experiment, with the modern method, 90.1 sections were needed to obtain a full macroscopic section, 36.8 sections with the heat extractor method, and 10.6 sections with the new mould. The quality of the histologic glass slides was superior with the new mould. The number of deeper levels required to obtain an adequate microscopic section was 5.9 for the modern method, 4.4 for the heat extractor method, and 2.3 for the new approach (new mould).
CONCLUSION: Our new approach with moulds and glass discs is simple and allows us to flatten the specimen (to obtain a complete tissue section) more reliably and efficiently compared with both the modern and the heat extractor methods. The new approach allows us to obtain these results in less time and with fewer histologic glass slides. Some other aspects are discussed.