Metastatic islet cell carcinoma: a potentially treatable cause of "carcinoma of unknown origin.".

A 55-year-old woman presented with diplopia secondary to an orbital mass. Physical examination showed a large ovarian mass. Further evaluation revealed these lesions to be metastases from a nonfunctioning pancreatic islet cell carcinoma, the first such case reported. Since these tumors can be responsive to chemotherapy, it is important to consider islet cell cancers in patients presenting with "metastatic carcinoma of unknown origin.