CASE 2047 Published on 23.01.2003

Carcinoid tumour in Meckel's diverticulum: sonographic diagnosis

Section

Abdominal imaging

Case Type

Clinical Cases

Authors

A. Hollerweger, P. Macheiner, E. Huebner

Patient

79 years, male

Categories

No Area of Interest ; Imaging Technique CT, Digital radiography, Ultrasound, Ultrasound-Power Doppler

No Procedure ; No Special Focus ;

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Clinical History

A patient with weakness, diarrhoea and moderate iron deficiency anaemia was admitted for an abdominal CT examination because endoscopic results were negative. Subsequently a small-bowel enema and a sonographic examination were performed.

Imaging Findings

The patient presented with a three-week history of weakness, lack of appetite and diarrhoea. Laboratory tests showed moderate iron deficiency anaemia (Hb: 10.4g/dl). Endoscopic examination did not reveal any explanatory reason.

The patient was admitted for a CT examination of the abdomen because of a mass in the mid abdomen suspected in an externally performed sonographic examination. CT scans showed a mass in the mesentery, probably representing lymph node metastases. For further evaluation a small-bowel enema and a sonographic examination of the mesentery and the small bowel were performed. Biopsy of the mesenteric mass and histological examination confirmed the diagnosis.

Discussion

Meckel's diverticulum is the most common anomaly of the small intestine affecting 1-3% of the population. Most Meckel's diverticula are incidentally discovered and about 20% may become clinically symptomatic due to complications (1,2). The most common clinical manifestations include small bowel obstruction (strangulation, volvulus, intussusception, herniation), diverticulitis, and bleeding. Neoplasms develop in approximately 1-5% of complicated diverticula. Carcinoid tumours are the most commonly reported tumours of Meckel's diverticula (3). Other malignant tumours include adenocarcinoma and leiomyosarcoma. Benign tumours include leiomyoma, angioma, neurinoma, and lipoma (4). Although more than 100 cases of carcinoid tumours in Meckel's diverticula have been reported in the literature, most of these tumours were found incidentally at surgery or at autopsy and the correct diagnosis is typically not established before surgery.

Small-bowel enema has been reported as being the most sensitive method for diagnosing Meckel's diverticulum, but false-negative results frequently occur (1). Angiography and radioisotope Meckel scan are used in patients with intestinal bleeding. Cross-sectional imaging methods may be of value in patients with inflammatory or tumorous complications. Carcinoid tumours can also be detected with I-123 octreotide studies due to the high density of somatostatin receptors in neuroendocrine tumours. Nevertheless the diagnosis of a Meckel's diverticulum remains difficult and even more so the diagnosis of a tumour in the diverticulum. To our knowledge thus far, imaging diagnosis of a carcinoid tumour in a Meckel's diverticulum has not been reported in the literature.

Primary malignant tumours of the small bowel are uncommon and they are often diagnosed at an advanced stage. Carcinoid tumours are characterised by a high rate of mesenteric and hepatic metastasis despite the usually small size of the lesion at the time of discovery. Up to 10% of carcinoid tumours of the small intestine are located in Meckel's diverticula and their biological behaviour is comparable with that of jejunoileal carcinoids (5). The tumours are typically hypervascularised and serotonin activity can lead to a carcinoid syndrome which is only rarely observed in Meckel's carcinoids. Despite early metastatic spread of carcinoids, the prognosis is better than in other malignant and metastasising tumours.

Differential Diagnosis List

Carcinoid tumour in Meckel's diverticulum and lymph node metastases of the mesentery

Final Diagnosis

Carcinoid tumour in Meckel's diverticulum and lymph node metastases of the mesentery

References

[1] 1. Mitchell AW, Spencer J, Allison DJ, Jackson JE. Meckel's diverticulum: angiographic findings in 16 patients. AJR Am J Roentgenol 1998 May;170(5):1329-33. (PMID: 9574611)

[2] 2. Blakeborough A, McWillliams RG, Raja U, Robinson PhJA, Reynolds JV, Chapman AH. Pseudolipoma of inverted Meckel's diverticulum: clinical, radiological and pathological correlation. Eur Radiol 1997;7(6):900-4. (PMID: 9228106)

[3] 3. Weber JD, McFadden DW. Carcinoid tumors in Meckel's diverticula.
J Clin Gastroenterol 1989 Dec;11(6):682-6. (PMID: 2685098)

[4] 4. Rossi P, Gourtsoyiannis N, Bezzi M, Raptopoulos V, Massa R, Capanna G, Pedicini V, Coe M. Meckel's diverticulum: imaging diagnosis. AJR Am J Roentgenol 1996 Mar;166(3):567-73. (PMID: 8623629)

[5] 5. Nies C, Zielke A, Hasse C, Ruschoff J, Rothmund M. Carcinoid tumors of Meckel's diverticula. Report of two cases and review of the literature.
Dis Colon Rectum 1992 Jun;35(6):589-96. (PMID: 1587179)

Case information

URL:	https://www.eurorad.org/case/2047
DOI:	10.1594/EURORAD/CASE.2047
ISSN:	1563-4086

Figure 1

Abdominal CT

CT scan shows a mass in the mesentery representing a large lymph node metastasis (arrow). Engorgement of the mesenteric vessels and slight thickening of ileal bowel loops is present because of tumorous infiltration.

The adjacent scan shows some small nodules (arrows) next to the large mass. Vascular engorgement and haziness of the affected mesentery is also present.

Some slices below, a circumscribed thickening of an ileal bowel loop (arrows) could retrospectively be identified (probably representing the tumour in the diverticulum).

Figure 2

Small-bowel enema

The small-bowel enema shows an ileal segment with thickened Kerckring folds. At the antimesenteric border a short outpouching (arrows) is visible. It probably represents the neck of the Meckel's diverticulum. The tumour in the diverticulum is not demonstrated because the lumen of the diverticulum is for the most part filled by the tumorous lesion.

Figure 3

Abdominal ultrasonography

Sonographic examination of the mid abdomen shows an ovoid mass in the mesentery (arrow) representing a large lymph node metastasis. Next to this mass asymmetric thickening of a small-bowel loop (arrowheads) is visible.

A longitudinal sonogram (4-9MHz linear array) of the ileal segment (arrowheads) demonstrates a circumscribed outpouching (arrows). The hypoechoic mucosal layer and the hyperechoic submucosal layer of this outpouching are indicative of a true diverticulum. In the diverticulum a small hypoechoic mass is visible (callipers).

A transverse sonogram at the same level also shows the tumour-containing diverticulum (arrow) of the ileal segment (arrowheads).

Power Doppler sonogram of the mesenteric mass demonstrates markedly increased colour flow consistent with a lymph node metastasis of a neuroendocrine tumour.