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Diagnosis and management of Merkel cell carcinoma

Krasagakis, K.

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doi: 10.1097/01.cmr.0000382800.84086.63
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Merkel cell carcinoma (MCC) is a rare primary neuroendocrine carcinoma of the skin with an aggressive biological behaviour and poor prognosis. Due to its rarity and the lack of appropriate studies, many issues regarding evaluation and management are often addressed based on case series or trials with small patient numbers. Clinical characteristics suggestive for diagnosis can be summarized under the acronym AEIOU (asymptomatic/lack of tenderness, expanding rapidly, immune suppression, older than 50 years, and ultraviolet-exposed site on a person with fair skin). Immunohistochemistry with antibodies directed against cytokeratins and neuroendocrine markers is required to support histology for definite tumor diagnosis. Absence of TTF1 expression can often differentiate MCC from small cell lung carcinoma. A four stage system is often used for classification of the clinical manifestations. Sentinel lymph node biopsy is a meaningful staging procedure for determining subclinical MCC spread to the lymph nodes. Optimal therapy for MCC is controversial and there is no broad consensus on disease management. Treatment for patients with primary tumor is surgery with wide local excision and the optional addition of radiotherapy to primary site and draining lymph node basin. In patients with nodal disease, surgery and adjuvant locoregional radiotherapy are commonly recommended. Patients developing distant disease have a poor prognosis with a median survival of 6–12 months. These patients may be candidates for palliative chemotherapy in the form of single-agent carboplatinum or etoposide, and combination chemotherapy. However, the effect of chemotherapy on survival has not been determined. Radiation may be used to palliate bone and brain secondary tumours. In MCC many questions remain unanswered up to now, and further studies are necessary for determination of optimal management.

© 2010 Lippincott Williams & Wilkins, Inc.