Merkel cell carcinoma (MCC) is a rare neuroendocrine malignancy of the skin characterized by high aggressiveness. Four main factors are implicated in its development: immunosuppression, ultraviolet radiation, age and the Merkel cell polyomavirus (MCPyV). | A case report of eyelid Merkel cell carcinoma occurring under treatment with nivolumab for a lung adenocarcinoma