Journal of Clinical and Aesthetic Dermatology

Psoriasis and Cutaneous Supplement 2016

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

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Page 26 of 35

U pdates on Psoriasis and Cutaneous Oncology: Proceedings from the 2016 MauiDerm Meeting [ S E P T E M B E R 2 0 1 6 • V O L U M E 9 • N U M B E R 9 ] S U P P L E M E N T T O T H E J O U R N A L O F C L I N I C A L A N D A E S T H E T I C D E R M AT O L O G Y S 2 3 gene on chromosome 12. Further, mutations were found in the mevalonate kinase (MVK) gene, which is important in lipid metabolism. The literature reports a case study of effective DSAP treatment using three treatments with a Q-switched ruby laser. 130 Other treatment options are associated with various drawbacks. Topical treatments have a low clearance rate and systemic retinoids are associated with side effects and do not produce long-term remission. PDT-ALA shows no benefit. Excision, cryotherapy, and ablative laser treatments appear to be the most effective and safe options although likely to produce scarring. 131 A therapeutic strategy that is evolving now for DSAP includes low-dose acitretin (10mg if possible) or, alternately, topical tazarotene 0.1% gel every night. Treatment with imiquimod 3.7% cream applied every other day (if tolerated) or every third day may be effective. Patients might also benefit from the use of 5- fluorouracil 5% on weekends. Although PDT was reported to be ineffective in treating DSAP, the following new protocol has been proposed: every two months, the patient undergoes ALA incubation under occlusion, followed by 16 minutes and 40 seconds of blue light performed with cryotherapy performed two weeks later to ablate what might still remain. It is important for dermatologists to raise awareness about DSAP and to offer patients therapeutic options. DSAP is a distressing skin condition particularly when lesions cannot be readily concealed by clothing. In some areas, support groups have emerged to help DSAP patients cope with their skin condition. Unusual Tumors Of sebaceous lesions, sebaceous gland carcinoma (SGC) is considered a particularly aggressive albeit uncommon neoplasm. It arises from the sebaceous glands in the skin, and in 75 percent of cases, treatment is made difficult by the periocular location of the lesions. The risk of local recurrence is high, but the metastatic risk is controversial and may be substantial. Although SGC tumors make up less than one percent of eyelid tumors, they comprise 1 to 5 percent of all eyelid malignancies. In such cases, a malignancy on the upper eyelid is two to three times more common than one on the lower lid and it typically afflicts patients in their sixties and seventies. Women are more often affected than men and it occurs more in Asians than other groups. Ocular SGC occurs when tumors arise in the periocular sebaceous glands. In most cases (50–70%), these tumors arise in the meibomian glands in the tarsal plates, but they may also arise in the glands of Zeis (eyelash cilia) in about 10 percent of cases. In <10 percent of cases, the tumors occur in the glands of caruncle. About 12 to 15 percent of ocular SGC can be described as multicentric or involving multiple periocular locations. The natural history of an ocular SGC begins subtly with a slowly enlarging, but painless, nodule that may exhibit yellowish or pinkish/red coloration. Since it grows slowly and is often asymptomatic and because it mimics other benign eye conditions (chalazion, keratoconjunctivitis, blepharoconjunctivitis, ocular pemphigoid), diagnosis of SGC can be delayed as long as three years. It may also resemble a BCC or SCC, although these latter two tumors occur more often on the lower than upper eyelid. Dermatologists presented with this condition should look for nonresolving "chalazion," a loss of cilia in the area, yellow streaks in the patient's conjunctiva, increased vascularity, and chronic but unilateral inflammation. Such signs should make the clinician suspect SGC. A chalazion is an inflammation of the Meibomian glands or the glands of Zeis, resulting in a painless, granulomatous inflammation. SGC is often misdiagnosed as a chalazion. Ocular SCG can appear on the pagetoid or intraepithelial area and spread onto the conjunctiva, resulting in keratoconjunctivitis or blepharo- conjunctivitis, which can be misdiagnosed as blepharitis. About a quarter of all SGC are extraocular, typically appearing on the parotid gland, head, or neck. They emerge as a nodule or papule and may be pink, tan, or yellow in color. Although unusual, there have been cases of SGC that occurred in the genitalia, ear canal, breast, nasal vestibule, and axilla. Although there is some sense that extraocular SGC are not as aggressive as ocular SVG, a retrospective study of 91 cases found that extraocular SGC have a recurrence rate of 29 percent and a metastasis rate of 21 percent. SCG are associated with Muir-Torre syndrome, although most SGC are of unknown etiology. Muir-Torre is a rare autosomal dominant genodermatosis, which may be a phenotypic variant of Lynch syndrome (hereditary nonpolyposis colorectal cancer syndrome). It is caused by a mutation in one of the mismatch repair genes, that is, MLH1, MSH2, or MSH6. Muir-Torre is characterized by the simultaneous or sequential development of a sebaceous neoplasm along with an internal malignancy. The internal malignancies are often visceral, low-grade tumors that occur most frequently in the colorectal area or genitourinary tracts. Not all patients with Muir-Torre will have a sebaceous carcinoma, but approximately 25 percent do. If it is suspected that a patient might have Muir-Torre, the sebaceous lesions should be tested for microsatellite instability. Immunohistochemical staining should be carried out to look for mismatch repair genes. Merkel cell carcinoma (MCC) is an unusual malignant tumor arising from the neuroendocrine cells with features of epithelial differentiation and in 1972 was described as a "trabecular carcinoma of the skin." Originally thought to be a sweat gland tumor, it is actually a cytoplasmic neurosecretory granule. Although rare, MCC is biologically aggressive and its incidence has tripled in the past two decades. It affects primarily the elderly Caucasian population and about 70 percent of

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