Journal of Clinical and Aesthetic Dermatology

Updates on Psoriasis & Cutaneou Oncology

An evidence-based, peer-reviewed journal for practicing clinicians in the field of dermatology

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S31 P r o c e e D i n G s JCAD jOUrnAl Of ClInICAl And AEsthEtIC dErMAtOlOgy september 2017 • volume 10 • number 9 • supplement comparable indications for MMs with rigorous microscopic margin assessment prior to reconstruction that might apply to both invasive and in-situ melanoma. the local recurrence rates of head and neck melanomas were evaluated in an observational cohort study conducted at a single academic center from 1997 to 2006 with a median follow up of 9.3 years. 1 68 all patients (n=806) underwent staged excision to treat poorly defned melanomas with unpredictable occult extension. local recurrence rates were 1.4, 1.8, and 2.2 percent at 5, 7.5, and 10 years, respectively. this study evaluated the association between the size of the lesion and the distance from the lesion needed to obtain a pathologically tumor-free margin. invasive melanoma required greater margins than melanoma in situ. the mean margin from lesion to clearance for melanoma in situ was 9.3±5.1mm and was 13.7±5.9mm for invasive melanoma. larger lesions recurred more often; for every 50mm 2 increase in the size of the clinical lesions, the patient had a nine-percent increase in the rate of local recurrence. local recurrence could also be associated the cutaneous tumor site, and immunosuppression (no immunosuppressed patient experienced a recurrence). this suggests that staged excision with comprehensive permanent section margin control of melanoma in chronically photodamaged skin on the head and neck confers on patients favorable recurrence rates when the melanoma margins are diecult to assess; recurrence rates are higher with traditional techniques. recurrence rates may increase over the long term; in this study, about a third of recurrences (36%) occurred after fve years. the larger lesion size was associated with the necessity for a greater margin for clearance, as was in-situ disease compared to invasive disease. 168 a novel technique for achieving optimal sections during staged lM excisions has recently been described in the literature. 169 this approach was developed to help overcome the high recurrence rates of lM with convention excision procedures and conventional MMs. since lM may be characterized by a wide subclinical spread, the traditional bread-loaf sectioning is unsatisfactory because it does not allow for complete visualization of margins. MMs relies on frozen tissue sections, which is not ideal for visualizing melanocytes. some new melanocyte stains have been introduced that enhance visibility but they are associated with higher costs and greater edort. 170 a newer technique relies on formaldehyde-fxed, paraen-embedded staged excision, which may permit better visualization. in this new approach, the apparent margins of the lesion are frst delineated under dermatoscopic evaluation. 169 When dealing with small lesions, two tissue strips (right and left) are excised vertically down to the deep fat layer; the 12 o'clock edge is marked in red, the six o'clock in blue. the outer edge of each strip is also marked in blue as this is the side embedded en face in the paraen. at the time of the frst layer, the central portion of the lesion is also excised and sent to the laboratory for standard serial sectioning to determine the possible presence of invasive disease. thin strips of tissue are prone to warping in formalin, so this technique uses glass slides to keep tissue strips as gat as possible during fxation. this technique allows for high- quality en face paraen-embedded sections, which enhance visualization of the margins. this type of staged marginal excision with mapping has emerged as an optimal approach for managing lM and lM melanoma. 161 lM melanoma and malignant melanoma in situ are often treated with MMs with frozen section immunochemistry. immunostains used in this connection have specifc advantages and disadvantages. Melan-a works well on frozen sections, but may not oder suecient specifcity. Microphthalmia transcription factor (Mitf) is a more specifc nuclear melanocyte immunostain, but it is less frequently used in clinical practice. in a study (n=16) of patients with either malignant melanoma in situ or lM melanoma, frozen sections from chronic sun-damaged skin with negative margin and 12 tumor samples were stained with both Melan-a and Mitf. 171 the mean melanocyte counts didered signifcantly (p<0.001) at 9.8 (Mitf) and 13.7 (melan-a). the negative margins for the mean melanocyte counts likewise didered signifcantly (p<0.001) with values of 8.84 (Mitf) and 14.06 (melan-a). the tumor mean melanocyte counts were 63.5 and 62.4 for Mitf and melan-a, respectively. thus, it appears that melanocyte density on tumor-free chronic sun- damaged skin is higher with melan-a than Mitf although Mitf provides a clear outline of the melanocyte nuclei. 171 it should be noted that there may be signifcant nonmelanocyte epidermal staining by melan-a in the negative margins and in chronic sun-damaged skin, but Mitf is an edective alternative to melan-a that enhances nuclear size and pleomorphism and allows for accurate quantifcation of melanocytes. in terms of cost, stain time, and tissue processing, Mitf and melan-a approaches are similar. Merkel cell carcinoma. Merkel cell carcinoma is an aggressive skin cancer associated with uv light exposure and the Merkel-cell polyomavirus (McPyv). 172 advanced Merkel cell carcinoma may respond transiently to chemotherapy but median progression-free survival is poor at about three months. 173 chemotherapy seems to confer little to no survival beneft with median survival around nine months; long-term survival is rare. 174 the programmed death 1 (PD1) immune inhibitory pathway appears to mediate localized immune

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