[Merkel cell carcinoma. Viral genesis and new therapeutic options?]

Merkel cell carcinoma (cutaneous neuroendocrine carcinoma) is a rare, highly malignant, neuroendocrine tumor of the skin with predominance in older patients. The tumor is most often located in the sun-exposed skin of the head, the neck and -as in our patient - the extremities. Notably, the tumor bears a high risk of an early regional lymph node as well as distant metastases. Clinically, only a presumptive diagnosis of Merkel cell carcinoma can be established. The definite diagnosis is made by histological and immunohistological methods. Surgical excision with a safety margin should be combined with sentinel lymph node biopsy. In advanced tumor stages (lymph node or visceral metastasis), a remission can be achieved by different chemotherapy schedules in combination with radiation. Recently, a previously unknown polyomavirus, named Merkel cell polyomavirus (MCV or MCPyV), has been identified in 80% of Merkel cell carcinomas. In the near future, these novel findings could be utilized to distinguish Merkel cell carcinoma from small round cell cancers and could lead to the development of new therapeutic options.