Pancreatic Islet Cell Tumor: Clinical Review of 12 Cases

ABSTRACT

BACKGROUND: Pancreatic islet cell tumors are very rare tumors that are classified into functioning, secreting hormone with specific symptoms, and nonfunctioning tumors without distinct symptoms. Because of their rarity, studies of them have been limitted. METHODS: We experienced 12 cases of pancreatic islet cell tumor at Samsung Seoul Medical Center from October 1994 to May 1998 and reviewed charts retrospectively. RESULTS: The mean age was 43.3 years; 46.3 years for those with functioning tumors. The most common symptom in nonfunctioning tumors was abdominal pain; other symptoms were abdominal mass, diabetes mellitus, and jaundice. With the functioning tumors, loss of conciousness and hypoglycemic sympathetic symptoms were present in all patients, and a seizure occurred in one case. The tumors were localized with abdominal CT in 91.7% (11 of 12), abdominal US in 87.5% (7 of 8), and selective angiography in 42.9% (3 of 7). The mean size was 1.7 cm in functioning tumors and 7.6 cm in nonfunctioning tumors. In 5 of the 6 cases, where the tumor was located in the pancreatic head, a pancreaticoduodenectomy was performed; enucleation was done in the other case. In the cases receiving a pancreaticoduodenectomy, choledochojejunostomy leakage was the only postoperative complication one case; there was a pancreatic pseudocyst in one case of enucleation. Of the functioning tumors, 3 (25%) were insulinoma; the remaining 9 (75%) tumors were nonfunctioning tumors. There were 4 cases (33.3%) of malignancies, and they were all nonfunctioning tumors. An immunohistochemical staining study showed evidence of multi-hormonal production in 45.5% of the cases, and all tumors showed a positive reaction to at least one hormonal marker. Two of the 3 insulinoma cases showed a positive reaction to insulin. Somatostatin was positive in 81.8% of the tumors, glucagon in 45.5%, and insulin in 18.2%. Chromogranin was positive in 71.4% of the tumors, synaptophysin in 60%, and neuron-specific enolase in 60%. CONCLUSION: There may be more cases of functioning tumors than have been reported and early diagnosis and treatment will reduce the incidence of malignancy. Abdominal CT or US is comparatively useful to localize the site of tumor and spiral CT angiography may be useful for the cases where nothing is detected with routine CT. Immunohistochemical staining is non-specific in classification of each islet tumor, but the positivity of any one of the hormonal markers may be useful in differentiating of pancreatic islet cell tumors from non-ilset cell tumors.