A comparison of scar revision with the free electron and carbon dioxide resurfacing lasers.

Laser scar revision was studied to measure the effects of targeting extracellular matrix protein versus tissue water on scar revision. We compared the free electron laser used at 7.7 microm (the amide III protein absorption band) to the carbon dioxide (CO2) laser and dermabrasion.Nude mice (n = 40) that had rejected skin grafts on their dorsal surface and developed mature scars were used as a model for scar revision. One-half of each scar was revised with either the free electron laser at 7.7 microm (32 to 38 mJ, nonoverlapping pulses delivered with a computerized adjustable pattern generator at 30 Hz, and two to three passes), a 100-microsec CO2 resurfacing laser (500 mJ, 5.0 Hz, and two to five passes), or dermabrasion. The untreated portion of each scar served as an internal control. Evaluation was by measurement of the clinical size of the scar using photography with quantitative computer image analysis to compare the data and histology to evaluate the quality and depth of the scars. The free electron laser at 7.7 microm was significantly better than the CO2 laser and dermabrasion for scar size reduction (p < 0.046 and p < 0.018). The CO2 laser and a highly skilled dermabrader were not statistically significantly different (p < 0.44). The result seen with less skilled dermabraders was significantly worse than all other methods (p < 0.009). The free electron laser at 7.7 microm, which is preferentially absorbed by the proteins of the extracellular matrix, provided better scar reduction than the CO2 resurfacing laser and dermabrasion. Dermabrasion by a skilled operator resulted in improvement similar to the results obtained with the CO2 resurfacing laser, but less skilled operators had significantly poorer results.

Potential utility of adjunctive histopathologic evaluation of some tumors treated by Mohs micrographic surgery.

BACKGROUND: Mohs micrographic surgery is a highly effective, tissue-conserving method for removing certain cutaneous neoplasms. Horizontal Mohs tissue sectioning permits complete histologic evaluation of the true surgical margin, but does not aim to evaluate the overall morphology of the tumor. Mohs surgery is designed primarily to answer the question "Is it all out?" as opposed to "What is it?" A preoperative biopsy is relied on, in most cases, to provide an accurate diagnosis. The histology from this biopsy might be the only view of the tumor if the first Mohs stage is clear. However, histopathologic review of small biopsies may sometimes give incomplete information about the entirety of the tumor. OBJECTIVE: To illustrate the potential utility of adjunctive histopathologic examination of some tumors treated by Mohs surgery. METHODS: We present four cases to illustrate situations where pre-Mohs biopsy provided incomplete information. The limitations of these biopsies was clarified after the tumor was visualized on a positive first Mohs layer and/or when the tissue was subsequently sectioned vertically. RESULTS: Cases of tumors where preoperative biopsies gave incomplete information are presented: sebaceous carcinoma versus basal cell carcinoma (BCC), invasive versus in situ squamous cell carcinoma (SCC), and SCC versus keratoacanthoma. CONCLUSION: The Mohs technique allows histologic examination of the complete surgical margin around cutaneous neoplasms, optimizing tissue sparing and resulting in superior cure rates. However, in rare cases additional evaluation of the tissue by vertical sectioning can provide important adjunctive histopathologic information that can effect ultimate patient management.

Combined sentinel lymphadenectomy and mohs micrographic surgery for high-risk cutaneous squamous cell carcinoma.

BACKGROUND: There are subgroups of cutaneous squamous cell carcinoma (SCC) that have a higher risk for both regional and distant metastasis. When cutaneous SCC does metastasize, it typically spreads first to local nodal groups. Sentinel lymph node (SLN) localization has been successfully used to evaluate nodal metastasis in breast carcinoma, melanoma, and other select tumors. It may also be useful in certain high-risk cutaneous SCCs. Currently, Mohs micrographic surgery is the treatment of choice for these tumors. METHODS: A patient presented with a high-risk recurrent SCC on the forehead. The regional nodal groups were clinically negative and radiographically negative by computed tomographic scan. Sentinel lymphadenectomy was performed by means of technetium 99m-radiolabeled sulfur colloid. The main tumor was resected with Mohs micrographic surgery. RESULTS: A left preauricular SLN was localized by lymphoscintigraphy. The SLN was located intraoperatively by means of a gamma probe and excised. Subsequent pathologic evaluation of the SLN was negative for evidence of metastatic SCC by light microscopy with hematoxylin and eosin, and with immunohistochemical stains for cytokeratins AE1 and AE3. The day after SLN excision, the tumor was removed via Mohs micrographic surgery with clear surgical margins after a total of 8 stages. Aggressive subclinical spread by both subcutaneous "skating" and perineural invasion was noted. CONCLUSION: The combination of Mohs micrographic surgery and sentinel lymphadenectomy is feasible and has theoretical utility in the management of a subset of cutaneous SCCs at high risk for metastasis. The ability of sentinel lymphadenectomy to identify regionally metastatic cutaneous SCC as well as the additive benefit of SLN and Mohs micrographic extirpation in the treatment of high-risk cutaneous SCC remain to be further clarified.

Dog-ears: a review.

BACKGROUND: The closure of any circular or asymmetric wound results in puckering or excess of tissue known as dog-ears. OBJECTIVE: Facility in managing dog-ears is an invaluable tool in cutaneous surgery due to its common presentation. METHODS: Methods for correcting dog-ears are extensively detailed in both the plastic and dermatologic surgery literature. This review provides a practical outline of nine methods of dog-ear correction along with pertinent schematic and clinical illustration. RESULTS: A comprehensive approach to dog-ears requires knowledge of tissue dynamics, adherence to proper surgical technique, and strategies for the management of dog-ears. CONCLUSIONS: A thorough understanding of dog-ear formation and correction allows the surgeon to choose the most appropriate management for dog-ears in any clinical setting.

Free electron laser infrared wavelength specificity for cutaneous contraction.

BACKGROUND AND OBJECTIVE: Short pulsed and scanned CO(2) lasers that target water molecules are currently used for cutaneous resurfacing. These CO(2) resurfacing lasers produce acute cutaneous contraction, which can be quantitated as a measure of the laser's effect. We postulated that targeting the vibrational and rotational modes of proteins with specific infrared laser wavelengths might be more effective at inducing cutaneous contraction than the CO(2) resurfacing lasers. STUDY DESIGN/MATERIALS AND METHODS: The Vanderbilt University Free Electron Laser (FEL) was used at wavelengths between 6.0-8.6 microm. The cutaneous contraction and histologic thermal damage observed was compared to that seen with a scanned CO(2) resurfacing laser. RESULTS: Peaks of cutaneous contraction at 7.2-7.4 and 7.6-7.7 microm were found, which were three-fold more efficient at producing cutaneous contraction than the 10.6 microm CO(2) laser. The 7.2 microm wavelength is associated with the CH bend of C-CH(3), 7.4 microm to the CH bend of O=C-CH(3), 7.6 microm to the C-C-C stretch, and 7.7 microm to the amide III (C-N-H) absorption band for proteins. Using light microscopy, an approximately 40 microm denaturation zone of dermal collagen was found at all FEL wavelengths tested, regardless of the effectiveness of cutaneous contraction. CONCLUSION: The mechanism of action of these infrared wavelengths on cutaneous contraction is unknown, but appears to be independent of the amount of collagen denatured as observed by light microscopy. Infrared lasers such as the FEL that target vibrational and rotational modes of proteins therefore hold promise for cutaneous application at selected wavelengths.

Collagenous fibroma (desmoplastic fibroblastoma).

Collagenous fibroma (desmoplastic fibroblastoma) is a recently described tumor that may arise in the subcutaneous tissue or skeletal muscle. We report a case of collagenous fibroma, occurring on the forehead of a 67-year-old man. An awareness of this entity is necessary to avoid confusion with other soft tissue neoplasms, especially extraabdominal fibromatosis.

Optimizing fluence and debridement effects on cutaneous resurfacing carbon dioxide laser surgery.

OBJECTIVE: To develop methods to compare carbon dioxide (CO2) resurfacing lasers, fluence, and debridement effects on tissue shrinkage and histological thermal denaturation. DESIGN: In vitro human or in vivo porcine skin samples received up to 5 passes with scanner or short-pulsed CO2 resurfacing lasers. Fluences ranging from 2.19 to 17.58 J/cm2 (scanner) and 1.11 to 5.56 J/cm2 (short pulsed) were used to determine each laser's threshold energy for clinical effect. Variable amounts of debridement were also studied. MAIN OUTCOME MEASURES: Tissue shrinkage was evaluated by using digital photography to measure linear distance change of the treated tissue. Tissue histological studies were evaluated using quantitative computer image analysis. RESULTS: Fluence-independent in vitro tissue shrinkage was seen with the scanned and short-pulsed lasers above threshold fluence levels of 5.9 and 2.5 J/cm2, respectively. Histologically, fluence-independent thermal depths of damage of 77 microns (scanner) and 25 microns (pulsed) were observed. Aggressive debridement of the tissue increased the shrinkage per pass of the laser, and decreased the fluence required for the threshold effect. In vivo experiments confirmed the in vitro results, although the in vivo threshold fluence level was slightly higher and the shrinkage obtained was slightly lower per pass. CONCLUSIONS: Our methods allow comparison of different resurfacing lasers' acute effects. We found equivalent laser tissue effects using lower fluences than those currently accepted clinically. This suggests that the morbidity associated with CO2 laser resurfacing may be minimized by lowering levels of tissue input energy and controlling for tissue debridement.

Stretch-induced nerve injury as a cause of paralysis secondary to the anterior cervical approach.

The anterior approach to the cervical spine, first described 40 years ago, has become a popular and widely used procedure by spine surgeons to expose the anterior vertebral bodies from C3 to T1. A significant complication of this procedure is transient or permanent ipsilateral recurrent laryngeal nerve paralysis. In a previous review at our institution of patients with hoarseness after an anterior cervical approach, 15 of 16 patients demonstrated right-sided paralysis. The asymmetry in the anatomic courses and lengths of the recurrent laryngeal nerves are proposed to place the right recurrent laryngeal nerve at an increased risk of stretch-related injury during this surgical procedure. We developed a cadaver model to evaluate the in-line stretch on the recurrent laryngeal nerve during the right- and left-sided approaches to the C4 and C7 vertebral bodies. To assess the difference in risk of injury to the two recurrent laryngeal nerves, we performed the anterior approach to the cervical spine in four anatomic positions: the left neck and right neck at the levels of C4 and C7 on 10 fresh human cadavers during the immediate postmortem period. The blades of a Cloward retractor were progressively spread to 2, 3, and 4 cm in the four anatomic positions while the corresponding degrees of ipsilateral recurrent laryngeal nerve stretch resulting from retraction were simultaneously measured. The left recurrent laryngeal nerve had sufficient redundancy in its course within the tracheoesophageal groove in 10 of 10 cadavers such that it exhibited no in situ stretch during the left-sided approach to either the C4 or C7 vertebrae. In contrast, the right recurrent laryngeal nerve has little redundancy in its course and is not protected within the tracheoesophageal groove. The right-sided approach to C7 resulted in an average in situ stretch on the ipsilateral recurrent laryngeal nerve of 12% and 24%, with 3 cm and 4 cm of Cloward retraction, respectively. The right-sided approach to C4 resulted in significant levels of stretch in 3 (30%) of 10 cadavers and no stretch in 7 (70%) of 10 cadavers. The relevance of these data is demonstrated by the review of numerous studies demonstrating the potential for significant neural damage with nerve stretch greater than 12%.