CASE 16692 Published on 09.04.2020

Intussusception secondary to a lipoma

Section

Abdominal imaging

Case Type

Clinical Cases

Authors

Alba Antón Jiménez, Andreu Antolin Redondo, Ignacio Delgado Alvárez, Daniel Moreno Martínez, Eva Castellà Fierro, Montse Adell Trapé, Marc Pérez Guitart

Institutions:
Department of Radiology, Hospital Vall d’Hebron, Autonomous Medical University of Barcelona

Contact information:
Email: alba.antonj@gmail.com

Patient

81 years, female

Categories
Area of Interest Abdomen, Colon, Emergency ; Imaging Technique CT
Clinical History

An 81-year-old female patient without any relevant previous medical background was admitted to the Emergency Room after a 10-day lasting medical history of vomits, oral intolerance and abdominal pain associated with diarrhoea in the last 48 hours.

Imaging Findings

Emergency abdominal X-ray showed diffuse dilated small bowel loops (Fig. 1). On suspicion of small bowel obstruction a contrast-enhanced abdominal CT scan was performed in which a bowel-within-bowel configuration was identified (Fig. 2 and 3 in sagittal and axial acquisitions respectively), showing:

  • Hyperdense outer ring (white arrow) as the intussuscipiens/receptor loop (caecum and ascending colon).
  • Hyperdense inner layer (green star) as the intussusceptum/donor loop (distal ileum).
  • Hypondense line (yellow arrow) between both rings, indicating the surrounding mesenteric fat folded within the intussuscipiens.
  • Mesenteric fat, mesenteric vessels (blue arrow) and lymph nodes (red arrow) telescoping along with the intussusceptum.

At the terminal ending of the intussusceptum a well-rounded mass with fat attenuation density was detected (Fig. 1, 4, 5 and 6 yellow star).

These findings were compatible with ileocolic intussusception due to a terminal ileum lipoma, with the appearance of target sign in sagittal view (Fig. 2) and pseudokidney/sausage-shaped mass sign in transversal view (Fig. 3).

Finally, it produced a retrograde dilatation of the small bowel loops with enhancing walls, mesenteric fat stranding and intraabdominal free fluid (Fig. 5 orange stars and arrow), suggesting small bowel compromise.

Discussion

A. Background

Intestinal intussusception accounts for 1% of all bowel obstructions in adults, and it is defined as the invagination of a segment of bowel with its mesenteric fold (intussusceptum) into an adjacent intestinal segment (intussuscipiens). The pathophysiology is still unclear, but it has been associated with dysrhythmic contractions and facilitated by the traction of a lead-point mass [1, 2].

The most common type is ileocolic intussusception and, unlike children, a demonstrable aetiology is found in 70-90% of adult cases [3]. Benign masses are more frequent in small bowel whereas adenocarcinoma is the most common cause in the large bowel invaginations. Lipomas are the most frequent benign cause of ileocaecal and colocolic intussusception in adults [1].

B. Clinical perspective:

Diagnosing intussusception in adults based on clinical presentation alone is challenging due to the overlap of symptoms with other diseases. The predominant symptoms in adults are those related to the bowel obstruction, but symptoms can also arouse from the own mass in cases of malignancy [3].

Intestinal lipomas are mainly asymptomatic until they are presented as an intussusception [1].

C. Imaging perspective:

Abdominal plain X-ray is usually not useful for the detection of intussusception but can play an important role in screening complications such as intestinal obstruction and pneumoperitoneum [2]. While ultrasound is the gold standard technique for diagnosing intussusception in children, CT is the most sensitive technique in adults.

CT findings of ileocolic intussusception include target and sausage-shaped sign, which consists of a concentric hyperdense double ring; distended colon with thickened wall (intussuscipiens) that contains in its lumen a segment of ileum along with a layer of mesenteric fat and vessels (intussusceptum) [2, 4].  Additionally, oedema and air can be found in the bowel wall in case of complication such as ischaemia, necrosis or gangrene [2].

Lipoma typically appears as a well-defined mass with homogeneous fat attenuation. 90% of them are located in the submucosa of the terminal ileum and colon and can be sessile or pedunculated [1]. 

MRI is not commonly used in the diagnosis of intussusception, but its sensitivity may be similar to CT with an enterography protocol [2].

D. Outcome

The patient underwent emergency surgery that confirmed ileocolic intussusception, with the presence of a rounded mass (yellow star, Fig. 7), which was then confirmed to be a lipoma in the pathology examination.

Contrary to paediatric population, treatment of intussusception causing obstruction in adults typically involves surgery, often with bowel resection [2, 3].

E. Take home message

  • Intussusception is an uncommon cause of small bowel obstruction in adults.
  • Main leading points tend to be malignant lesions. However, other aetiologies should be taken into account (lipoma being the most frequent benign cause).
  • CT is the gold standard for the diagnosis of intestinal intussusception in adults.
  • Typical CT findings of ileocolic intussusception include bowel-within-bowel appearance (target and sausage-shaped sign).
  • Rapid diagnosis and treatment (often surgery) is required due to a potential vascular bowel compromise.

Written informed patient consent for publication has been obtained.

Differential Diagnosis List
Small bowel obstruction secondary to an ileocolic intussusception due to a terminal ileum lipoma.
Ileocolic intussusception due to Meckel diverticulum: appears as a central core of fat attenuation rounded by a soft-tissue collar due to its inversion.
Ileocolic intussusception due to adenomatous polyp or inflammatory fibroid polyp.
Ileocolic intussusception due to distal and terminal ileal B-cell lymphoma.
Other causes of malignant or benign intestinal obstruction.
Final Diagnosis
Small bowel obstruction secondary to an ileocolic intussusception due to a terminal ileum lipoma.
Case information
URL: https://www.eurorad.org/case/16692
ISSN: 1563-4086