A Merkel cell carcinoma presenting as a solitary lymph node metastasis without a primary lesion. Report of a case and review of the literature.

Merkel cell carcinoma is an uncommon, aggressive neuroendocrine tumour of the skin. At presentation regional lymph nodes are involved in approximately one third of the patients. In this report a patient is presented in whom Merkel cell carcinoma presented as a solitary lymph node metastasis with an unknown primary skin lesion. The diagnosis of unknown primary merkel cell carcinoma including the use of immunohistochemical markers and treatment options based on data from the literature are discussed.