Mesenteric changes in an ultrasound examination can facilitate the diagnosis of neuroendocrine tumors of the small intestine

Abstract

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.

Keywords: abdominal ultrasound; diagnosis; mesenteric lesions; neuroendocrine tumors; small intestine.

Fig. 1

Metastatic lymph nodes (N) in the mesentery reflect the presence of a small intestinal carcinoid tumor (not shown in the figure)

Fig. 2

One view shows irregular infiltration of a carcinoid tumor of the terminal ileum (C) and a sentinel lymph node (N)

Fig. 3

Carcinoid tumor (12 mm) of the small bowel (not shown in the figure). In this case, an irregular hypoechoic and vascularized infiltration is visible in the mesentery

Fig. 4

An irregular hypoechoic mass in the mesentery is the only manifestation of a carcinoid tumor in the ileum (not shown in the figure)

Fig. 5

Two views of a hypoechoic mass (4 cm) in the mesentery of a 32-year-old patient with the body mass of 122 kg as the only ultrasound sign of a carcinoid tumor in the ileum

Fig. 6 A

A sizeable, partially calcified hypoechoic mass (M) in the mesentery is a prominent manifestation of a carcinoid tumor in the ileum (not shown in the figure)

Fig. 6 B

The same case. The vascularization of the lesion shown in a different view

Fig. 7 A

One view captures a carcinoid tumor in the ileum (C) and a hypoechoic mass in the mesentery, which is greater than the primary lesion

Fig. 7 B

The same patient. This view shows only the bean-shaped carcinoid tumor in the intestine, visualized with the use of a linear probe

Fig. 7 C

The same patient, but the lesions are visualized in CT enteroclysis. The tumor of the terminal ileum (C) is of an identical shape to that visualized by ultrasonography. Moreover, two affected mesenteric lymph nodes are visible

Fig. 7 D

The same patient. A different CT layer. It presents the mass (M) in the small intestine and two different affected mesenteric lymph nodes (n). Moreover, two metastatic foci were detected in the right lung (not shown here)

Fig. 8 A

Carcinoid tumor (2 cm) of the ileum with features of hyperemia and with the markedly hyperechoic mesentery

Fig. 8 B

The same patient. Dilated loops of the small intestine surrounding the thickened mesentery (M) indicate ileus

Fig. 9

Thickened mesentery shows lesions that are difficult to visualize. They are an ultrasound representation of a carcinoid tumor in the small intestine (not shown in the figure)