Occult functioning insulinomas: which localizing studies are indicated?

An occult insulinoma refers to a biochemically proven tumor with an anatomic site that remains indeterminate before operation. The amount of radiologic localization for such patients is debatable.Sixty-five patients with sporadic insulinomas were surgically treated at the Mayo Clinic between January 1980 and December 1990. True occult tumors were present in 31% of these patients (n = 20). Thirty-eight negative preoperative localization studies...