Merkel cell carcinoma of unknown primary with lymph node and mesenteric metastasis involving the pancreas and duodenum.

Merkel cell carcinoma (MCC) of skin is a rare, aggressive cutaneous malignancy of neuroendocrine origin. MCC predominantly affects elderly Caucasians and has high predilection for sun exposed areas. Histologic exam and immunohistochemical profile is required to establish the diagnosis.