Non-functioning islet cell tumors of the pancreas--a multicentric clinical study in Taiwan

Islet cell tumors of the pancreas are rare. Functioning tumors are characterized by the symptoms induced by the hormones they secrete. The clinical behaviors of non-functioning tumors are quite different. In this retrospective study, we scrutinized 16 patients with non-functioning islet cell tumor in three tertiary university hospitals in Taiwan during a 20-year period.

There were 12 women and 4 men with a mean age of 47 years. Body-weight loss, abdominal pain and palpable mass were the most frequent symptoms.

The mean size of these tumors was 8.9 cm in diameter. Ten tumors were located at the tail of pancreas, the other 6 located at the head. Except for hyperbilirubinemia in 2 patients, none of the patients with non-functioning islet cell tumor showed abnormalities of laboratory data including serum tumor markers. Preoperative detection of these tumors by imaging modalities was not difficult due to the large size of the tumors. However, differentiation with functioning tumor or ductal cell carcinoma required clinical and imaging correlation. Fourteen tumors were malignant including 8 with regional lymph nodes involvement, 3 with locally microscopic invasion, 2 with hepatic metastasis and 2 with nearby organ invasion.

Even with its malignant behavior, non-functioning islet cell tumor still possessed a good prognosis after adequate surgical removal in comparison with a higher mortality rate of ductal carcinoma of the pancreas.