their head in the opposite direction and then drawing a vertical line down from the mastoid process approximately 6 cm to the posterior border of the sternocleidomastoid muscle. A 3-cm circle at this point delineates the fourth danger zone (Fig. 31.7). The spinal accessory nerve, which courses within the fascia investing the sternocleidomastoid and trapezius muscles, may be avoided by staying within the subcutaneous fat when performing sugery in Erb’s point. In addition to the spinal accessory nerve, which supplies motor innervation to the neck and shoulder, the greater auricular nerve (C2 and C3) is also located in the Erb point and provides sensory innervation to the neck and ear. Damage to the greater auricular nerve results in loss of sensation to the periauricular area, while damage to the spinal accessory nerve results in a “winged scapula” and weakness in the neck and shoulder, an unfortunate result which is often permanent and requires nerve grafting to restore function.

Summary: Tumor Recurrence

•Mohs surgery offers the lowest possible recurrence rates for BCC and SCC.

•Factors associated with increased tumor recurrence include: large size, poor differentiation, delay in treatment, tumor location in the central face, and the presence of chronic lymphocytic leukemia.

31.4Tumor Recurrence

It is generally accepted that Mohs surgery provides the lowest possible recurrence rates of any treatment modality for Basal Cell and Squamous Cell carcinoma (Fig. 31.8). The 5-year recurrence rate of BCC treated with Mohs surgery has been reported to range between 1% and 3% for primary tumors and 5% and 7% for recurrent tumors [19–22]. For SCC, the 5-year recurrence rate has been variously reported to range from 3% to 5% for primary tumors and 6% to 10% for recurrent lesions [19, 20, 23]. The largest of these studies reported by Dr. Mohs himself showed a 1% 5-year recurrence rate in 8,643 tumors treated by Mohs chemosurgery [19]. Two recent publications from Australia prospectively evaluated the 5-year recurrence rates of BCC and SCC treated by Mohs surgery. For BCC, the authors found that the factors associated with a higher risk of recurrence were prior recurrence, longer time before surgery, and more stages of Mohs for tumor clearance [24]. Prior studies had identified large tumor size, aggressive histology, and location in the facial “H-zone” to be risk factors for recurrence. For SCC, the risk factors were larger size, poor differentiation, and prior recurrence [25]. The reported overall recurrence rate for BCC was 1.4% for primary and 4% for recurrent tumors, while for SCC, the recurrence rate was 2.6% for primary and 5.9% for recurrent lesions. Other factors associated with a higher risk of recurrence of SCC include tumor depth greater than 4 mm (Clark level IV), tumor location in previous

areas treated by radiation, thermal injury, Bowen’s disease, chronic ulcers, as well as specific sites such as the ear, lips, and genital area.

Another risk factor for recurrence of both BCC and SCC which has received significant attention recently is the concomitant presence of chronic lymphocytic leukemia (CLL) [25, 26]. Patients with CLL undergoing Mohs surgery have been reported to have a sevenfold higher risk of recurrence of SCC and a 14-fold higher increase in recurrence of BCC when compared to controls. The reasons for this increased risk are not completely clear but may include an impaired host immune response as well as positive Mohs margins being obscured by dense lymphocytic infiltrates. It has been suggested that dense peri-tumoral infiltrates may be a marker for patients with undiagnosed CLL, and further work-up should be done in these cases. In summary, Mohs surgery offers the lowest possible rates of tumor recurrence. Risk factors for tumor recurrence include, large size, poor differentiation, a prior recurrence, a long delay in treatment, and the presence of CLL.

Summary: Medication Complications

•Medication complications are rarely encountered in Mohs surgery.

•True lidocaine allergy is very rare.

•Lidocaine with epinephrine may be used safely on the digits.

•Allergy contact dermatitis to topical antibiotics is very common

31.5Medication Complications

The most commonly employed medicines in Mohs surgery are lidocaine and epinephrine. They are both remarkably safe and free of serious complications, yet there are several possible side effects that should be considered when employing these medications. Lidocaine, along with bupivacaine and mepivacaine, belong to the amide class of local anesthetics. Due to an improved safety profile and decreased allergic potential the amide anesthetics have largely replaced the earlier ester class, which includes procaine, tetracaine, and benzocaine. True lidocaine allergy is very rare and most patients reporting an allergy to lidocaine

actually experienced a prior vasovagal reaction. Lidocaine hypersensitivity can be either type I immediate hypersensitivity or type IV delayed hypersensitivity. Both are very rare, with type I reported more often. A French study re-challenged 199 patients with reported lidocaine allergies, of these, only 1 developed an allergic reaction [27]. In an Israeli study of 236 patients referred for evaluation of local anesthetic allergy, skin prick and intradermal testing failed to demonstrate a single reaction [28]. In another study, 183 patients with supposed lidocaine allergy were patched tested, 4 positive reactions were reported, 2 of these patients also positive reactions to intradermal injection [29].

The maximum recommended dose for plain lidocaine is 4.5 mg/kg, whereas the maximum recommended dose for lidocaine with epinephrine is 7.0 mg/kg. The maximum dose should not be administered to the patient for at least 2 h. Alam et al. measured the peak lidocaine serum concentrations during and after Mohs surgery in 19 patients, the maximum reported concentration in any patients was 0.3 mg/ml [30]. This level is well below the minimal concentration of 5 mgml needed for objective signs of lidocaine toxicity to develop. At the 5 mg/ml level, signs of lidocaine toxicity include paresthesias, muscle fasciculations, and tinnitus. The authors conclude that even relatively large volumes of 1% lidocaine with epinephrine are associated with serum levels well below toxic levels.

Epinephrine is also a very safe medication. Historically there has been controversy as to the safety of using epinephrine in the digits. Several recent reviews failed to detect any reported cases of finger necrosis or gangrene with commercial preparations of lidocaine with epinephrine [31, 32]. All the reported cases were reported with earlier ester anesthetics or with noncommercial preparations of unknown concentration. Additional evidence for the safety of low concentration 1:100,000 epinephrine comes from a review of 59 cases of accidental auto-injection with high concentration 1:1,000 epinephrine (Epi-Pen) [33]. The review found no reported cases of tissue necrosis even in 32 patients who received no treatment. It seems that there is no doubt, that dilute epinephrine is safe for use in the fingers and toes. One situation in which the use of plain lidocaine may be considered is when performing surgery on a pregnant patient. Although small doses are probably safe, epinephrine is a category C medication, whereas plain lidocaine is category B.

Fig. 31.9 Allergic contact dermatitis to Neosporin

Other medications which may cause side effects include topical antiseptics. Chlorhexidine may cause an acute keratitis if it enters the eye, so care must be taken when using this antiseptic in the periocular area. Chlorhexidine is also toxic to the inner ear and should not be used for procedures in the periauricular area. Hexachlorophene, another topical antiseptic, has been associated with seizures and neurotoxicity, especially in small children. Povidone-iodine is the most commonly used disinfectant in skin surgery. Rare reports of contact dermatitis to this agent have been reported, so patients with known iodine allergy should avoid exposure. A recent publication demonstrated that chlorhexidine/ alcohol was superior to povidone-iodine in preventing wound infection in clean-contaminated surgeries [34].

“Should I apply Neosporin to the wound?” is a frequent question asked by patients after surgery. Neomycin and bacitracin along with polymyxin b are the active ingredients in Neosporin or triple antibiotic. In the years 2005–2006, neomycin and bacitracin were the fifth and sixth most common reported allergens in the patch test results of the North American Contact Dermatitis group [35]. In a landmark study published in 1996, Smack et al. showed there was no statistical difference in wound infection rates among patients undergoing dermatological surgery who were given either white petrolatum or bacitracin ointment [36]. The authors concluded that bacitracin offered no advantage

over white petrolatum in preventing infection and increased the risk for contact dermatitis (Fig. 31.9).

In conclusion, toxic levels of lidocaine are very rarely encountered during Mohs surgery, lidocaine with epinephrine is safe to use on the digits, chlorhexidine/alcohol may offer improved efficacy over povi-

Summary: Recently Described Complications

•Eruptive SCCs and keratoacanthomas may develop in areas of prior surgery.

•Treatment of these lesions is difficult and often requires repeated Mohs surgeries and systemic retinoids.

•Cerebral air emboli may occur during Mohs sugery of the scalp and skull when the patient is placed in the seated position.

done-iodine as a surgical scrub, and white petrolatum is an ideal postoperative ointment.

31.6Recently Described Complications

Numerous reports have detailed the development of eruptive keratoacanthomas and squamous cell carcinomas after skin cancer surgery [37–39]. The mechanism behind the development of this pathergy type of reaction is not known but may be due to field cancerization. The stimulus of postsurgical wound healing may be sufficient to drive the development of subsequent tumors in an area of mutated epithelium. Thankfully, this is a rarely reported phenomenon as treatment is often challenging and may require multiple Mohs procedures as well as oral retinoids to control the development of new lesions.

The development of cerebral air emboli following Mohs surgery has also been reported in two patients [40]. Both patients underwent outpatient Mohs surgery for SCCs of the scalp, both were placed in the seated position, and both had extensive resections including removal of periosteum. Both patients developed neurological dysfunction and were rapidly transported to the emergency room. Luckily, the first patient recovered without sequelae; unfortunately the second patient suffered severe impairment to his language and a left hemiplegia and died shortly thereafter. After reviewing

the literature, the authors concluded that having the patient in the seated position is a risk factor for the development of cerebral air emboli as it lowers the hydrostatic pressure within the cerebral vessels. The authors therefore recommend placing the patient in the recumbent position during surgery of the scalp involving the outer layers of the skull.

Summary: Conclusion

•Mohs surgery is an extremely safe procedure.

•Most patients should continue their anticoagulants during Mohs surgery.

•Antibiotic prophylaxis is rarely required and in general not recommended.

•Nerve damage can be avoided by a thorough knowledge of the relevant anatomy.

31.7Conclusion

Mohs surgery is an extremely safe and effective treatment for cancers of the skin. Serious complications are, in general, very rare and most all can be avoided by a careful and conscientious approach to the individual patient. Most patients can safely continue their anticoagulants during Mohs surgery and thus avoid the risk of serious thrombotic complications. Antibiotic prophylaxis is rarely required thus avoiding the risks of antibiotic allergy and resistance. Nerve damage can usually be avoided by a detailed knowledge of facial anatomy, and when it does occur spontaneous improvement can often be expected. Tumor recurrence is rare after Mohs surgery. Increased surveillance for recurrence may be indicated in certain patients with large tumors, poorly differentiated tumors, long neglected tumors, and with CLL. Medication complications are not common in Mohs surgery and most can be avoided by limiting the use of topical antibiotics after surgery. It is our hope that Mohs surgery can continue to set the standard of excellence for safety and efficacy in skin cancer surgery.

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J.I. Hui (*) • D.T. Tse

Department of Ophthalmic Plastic, Orbital Surgery

and Oncology service, Bascom Palmer Eye Institute, Miami, FL, USA

e-mail: jhui@med.miami.edu

Summary: Anterior Lamellar Defects – Summary

Statement

•Anterior lamellar defects may be closed in numerous ways, including: (1) primary closure, (2) full-thickness skin graft, or (3) local tissue flap. The posterior lamella must first be examined closely to ensure it is intact. Anterior lamellar repair should not induce eyelid malposition or distortion.