FROM THE ARCHIVES OF THE AFIP - ISLET-CELL TUMORS OF THE PANCREAS - CLINICAL, RADIOLOGIC, AND PATHOLOGICAL CORRELATION IN DIAGNOSIS AND LOCALIZATION

Islet cell tumors are rare pancreatic or peripancreatic neoplasms that produce and secrete hormones to a variable degree. These tumors are b est divided on clinical grounds into those that produce a recognizable , clinically evident endocrine syndrome (ie, functioning) and those th at exhibit no clinical evidence of hormone production (ie, clinically silent). Clinically silent tumors produce symptoms due to mass effect because of their large size. They are often partially cystic or necrot ic. Functioning islet cell tumors usually manifest earlier in the cour se of the disease because of the distinctive signs and symptoms of the associated endocrine syndrome. Clinically silent and functioning tumo rs cannot be histologically distinguished reliably even with the use o f immunohistochemical stains. Insulinoma and gastrinoma, the two most common functioning lesions, are typically small homogeneous masses. Ot her functioning islet cell tumors include glucagonoma, somatostatinoma , vipoma, and adrenocorticotropic hormone-producing tumor. Larger tumo rs are associated with calcification, cystic degeneration and necrosis , and a more aggressive behavior (local and vascular invasion as well as distant metastases). There are many different techniques for detect ion and characterization of these lesions that are usually chosen acco rding to the radiologist's experience and preference. Treatment and pr ognosis of these lesions depend on the hormone produced, their size, a nd their behavior.