Abdominal imagingCase Type
Alba Antón Jiménez, Andreu Antolin Redondo, Ignacio Delgado Alvárez, Daniel Moreno Martínez, Eva Castellà Fierro, Montse Adell Trapé, Marc Pérez GuitartPatient
81 years, female
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.
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:
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.
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 . 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 .
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 .
Intestinal lipomas are mainly asymptomatic until they are presented as an intussusception .
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 . 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 .
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 .
MRI is not commonly used in the diagnosis of intussusception, but its sensitivity may be similar to CT with an enterography protocol .
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
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 Marsicovetere P, Ivatury SJ, White B, Holubar SD (2017) Intestinal Intussusception: Etiology, Diagnosis, and Treatment. Clin Colon Rectal Surg 30(1):30-39 (PMID: 28144210)
 Azar T, Berger DL (1997) Adult Intussusception. Ann Surg 226(2):134-8 (PMID: 9296505)
 Jaffe T, Thompson WM (2015) Large-Bowel Obstruction in the Adult: Classic Radiographic and CT Findings, Etiology, and Mimics. Radiology 275(3):651-63 (PMID: 25997131)