Merkel cell carcinoma of unknown primary site

Abstract

Merkel cell carcinoma is an uncommon and aggressive primary neuroendocrine skin malignancy which mostly affects the extremities and the head and neck region of elderly patients. Merkel cell carcinoma occurs with increased frequency in sun-exposed areas, in individuals exposed to arsenic and in immunosuppressed patients. Many patients with Merkel cell carcinoma present with other malignancies, mainly skin cancers. Characteristic features are frequent recurrences and regional and distant metastases. Mortality rates range from 20 to 65 per cent. The mainstay of treatment is surgery, with wide local excision, and adjuvant radiotherapy is usually administered. Merkel cell carcinoma of unknown primary site is rare, and the majority of the few cases described have not been from head and neck areas. We present a case of Merkel cell carcinoma of unknown primary site, with upper neck and distant metastases.