Neuroendocrine tumors make up an interesting pathology of a variable clinical picture, prognosis, localization, endocrine activity and degree of malignancy. Aim: The aim of this paper is to assess whether ultrasonography can be helpful in diagnosing neuroendocrine tumors in the small intestine by analyzing changes in the mesentery. Material and methods: From 1996 to 2013, we encountered 17 patients (9 women and 8 men at the mean age of 57) with a neuroendocrine tumor in the small intestine. The diagnosis was confirmed in all patients by pathomorphological examinations. All retrospectively analyzed patients (n =17) had an abdominal US examination conducted in accordance with the previously mentioned protocol. Results: Primary neuroendocrine tumors were visualized ultrasonography in 13 of 17 patients (76.5%). In the remaining 4 patients, tumors in the small bowel were diagnosed in CT enteroclysis (n = 3) and conventional enteroclysis (n = 1). Somatostatin receptor scintigraphy and CT enteroclysis supplemented the ultrasound result by providing information about the stage of the disease in 7 cases. In most of the 17 patients with a neuroendocrine tumor diagnosed by ultrasound (n = 11, 64.7%), changes in the mesentery were prevailing pathological signs that raised suspicion and, consequently, helped localize the primary lesion. The hypoechoic mesenteric lymph nodes were the greatest (9–18 mm), well-circumscribed, and the largest of them showed signs of vascularization. The size of hypoechoic lesions in the mesentery ranged from 25 to 53 mm. These lesions showed moderate blood flow. All of them were single, usually poorly circumscribed; two lesions showed slight calcifications. Conclusions: In an abdominal US examination, 2/3 of patients with neuroendocrine tumors in the small bowel manifest secondary lesions in the mesentery which are easier to visualize than the primary focus. 30% of them are manifested as hypoechoic masses. The detection of such lesions should prompt the search for the primary focus in the small intestine.

neuroendocrine tumors, small intestine, mesenteric lesions, abdominal ultrasound, diagnosis