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We read with interest the report of Hsuan et al.1 The authors present a case series of 55 patients with basal cell carcinoma on the eyelids. There are no details regarding the size or histological subtypes of basal cell carcinoma in the results and therefore it is difficult to assess the applicability of the results to other groups of patients who may have more or less severe basal cell carcinoma. The authors make several generalisations regarding Mohs surgery that we believe are unsubstantiated and we wish to take the opportunity to clarify a few points.
The essence of Mohs micrographic surgery is 100% histological frozen section margin control. There is no other technique that enables 100% margin examination, including the authors’ bread loaf section technique. Mohs micrographic surgery has 99% 5 year cure rates for basal cell carcinoma because of the thorough margin examination. In distinction, standard bread loaf section technique examines approximately 0.1% of the surgical margin, with an increased potential to miss infiltrative tumour extensions. Because the bread loaf technique is least likely to accurately detect a positive margin, many surgeons employ a tangential peripheral section analysis as a means of obtaining more thorough examination of the margin.
Mohs micrographic surgery has another advantage, which is true tissue sparing. The margin of normal skin removed during Mohs micrographic surgery may be as little as 0.5 mm. When operating on the eyelid, 1 mm can be the difference between sacrifice and preservation of a critical structure (that is, punctum). The authors sacrificed 2 mm on both sides of the skin cancer, which in some cases may have resulted in up to 3 mm of unnecessary skin removal. This could result in more complicated reconstruction for patients.
The authors state that their patients were happy to have multiple operative sessions. For patients undergoing Mohs micrographic surgery, complete tumour removal is accomplished in one session, with reconstruction performed on the same day as tumour extirpation. The inconvenience to patients associated with staged re-excision after 48 hours of histological examination and then a final stage reconstruction 48 hours after the last histological sample is taken should not be underestimated. Patients in general are pleased with their care based primarily with their interaction with the physicians. However, I sincerely doubt that any patient would choose three surgical interventions over 5 days rather than one surgical intervention with 100% margin control in 1 day.
The authors state that Mohs surgery is “too expensive.” This statement is unsubstantiated. In a cost analysis by Cook and Zitelli,2 Mohs surgery was found to be similar in cost to excisional surgery and less expensive than frozen section analysis. With three potential operative encounters, the cost of staged excision of basal cell carcinoma in the United States would exceed that for Mohs micrographic surgery with reconstruction on the same day. It is also important to note that the pathological charges are included in the Mohs surgery fee, as the Mohs surgeon functions as both the surgeon and pathologist. Therefore, pathology charges generated for multiple staged re-excisions must be included in any calculation of cost associated with staged excision.
The authors characterised Mohs surgery as “laborious.” I would argue that one doctor performing a very efficient tissue sparing operation all in a matter of 2–4 hours, a typical duration for Mohs surgery and reconstruction, with the pathology included within that time frame and fee, is both cost efficient and labour efficient. Mohs surgery has been especially designed for accuracy, tissue sparing, convenience, cost efficiency, and labour efficiency.
Mohs surgeons are expert in the complete removal of complex skin cancers, particularly on the central facial area. Mohs surgeons work closely with our colleagues in oculoplastic surgery in the United States to coordinate expert reconstruction of the resultant defects. In places where Mohs surgery is less available, close communication between the surgeon and pathologist, and tangential vertical margin processing may offer a reasonable therapeutic option, although one that is more inconvenient, costly, and laborious for patients and physicians alike.