Published on 19/03/2015 by admin
Filed under Dermatology
Last modified 19/03/2015
This article have been viewed 1326 times
E. Eugene Bain, III and Nathalie Zeitouni
Evidence Levels: A Double-blind study B Clinical trial ≥ 20 subjects C Clinical trial < 20 subjects D Series ≥ 5 subjects E Anecdotal case reports
Merkel cell carcinoma (MCC) is a rare cutaneous neuroendocrine carcinoma with aggressive clinical behavior, initially described by Toker in 1972. MCC typically affects older individuals, with the median patient age being 69 years. Immunosuppressive conditions such as chronic lymphocytic leukemia, human immunodeficiency virus and solid organ transplantation have been linked to increased risk of developing MCC. In terms of the pathogenesis of MCC, there is evidence for both infectious and environmental factors. Support for viral promoted oncogenesis came with the discovery in 2008 of the Merkel cell polyomavirus. Ultraviolet (UV) radiation has also been described as a risk factor for the development of MCC, as most of these tumors develop at sites of sun damage with UV-associated cutaneous malignancies. The most common location is the head and neck region followed by the trunk.
Given the rarity of this malignancy, randomized controlled trials for therapies are lacking. As such, much of the data regarding the success of treatment modalities such as surgery, radiation and chemotherapy stems from case series or retrospective analyses of patient data. An algorithmic approach to treatment has been put forth by the National Comprehensive Cancer Network (NCCN).
Imaging is employed for initial work-up and staging (as clinically indicated) to detect regional or distant metastases. This may be done with either computed tomography (CT), magnetic resonance imaging (MRI) or FDG positron emission tomography-CT (PET-CT), though studies have not shown a convincing advantage for functional imaging modalities.
Surgical removal of the primary tumor is an important component of any treatment strategy, either with standard wide local excision or Mohs micrographic surgery. In addition to excision of the primary tumor, sentinel lymph node biopsy (SLNB) is often recommended, if feasible, given the tendency of the tumor to metastasize. Evidence of clinically positive lymphadenopathy at the time of presentation will often prompt lymphadenectomy.
Radiation may be used adjunctively for disease control, to the primary site as well as the draining lymph node basin. Not all studies have shown a statistically significant benefit with radiation therapy. Moreover, recurrences may respond less well to radiation therapy. In addition to traditional applications of radiation therapy, newer methods have been reported including surface-mold computer-optimized high-dose-rate brachytherapy. Chemotherapy is sometimes employed, though less evidence supports its use. Isolated limb perfusion or infusion has been used successfully for in-transit metastases.
Diagnostic imaging
Sentinal lymph node biopsy
Maury G, Dereure O, Du-Thanh A, Mariano-Goulart D, Guillot B. J Eur Acad Dermatol Venereol 2011; 25: 1420–7.
This retrospective study of 15 patients compared clinical staging with (18)FDG PET-CT as well as conventional CT. Investigators found that FDG PET-CT imaging did not change disease staging and/or management based on a combination of clinical examination, SLNB and conventional CT. Conventional CT and FDG PET-CT demonstrated identical sensitivity and specificity in this small patient cohort.
These results support data of other studies which have shown similar sensitivities when comparing functional and anatomic imaging modalities.
Treatment of Skin Disease Comprehensive Therapeutic Strategies 4e
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