Small nonfunctioning islet cell tumor in the body of the pancreas: report of a case.

Islet cell tumors of the pancreas are uncommon, and nonfunctioning tumors are even rarer than functioning ones. We report the case of a 67-year-old woman with a small nonfunctioning islet cell tumor, 6 x 5 mm in diameter, which was detected incidentally by ultrasonography, and subsequently confirmed by double-helical computed tomography. Diagnosis was established by histopathological examination after 80% distal pancreatectomy with splenectomy, and by various laboratory tests. Histologically, the islet cell tumor showed highly cellular spindle or epithelioid cells, which were positive for Grimelius stain. Immunohistochemical examination revealed that the tumor cells were positive for chromogranin A, but negative for somatostatin, insulin, glucagon, and gastrin. Its small size, location, and benignity make this a very rare type of nonfunctioning islet cell tumor.