Adult colocolic intussusception due to colonic mass

Clinical History

A 55-year-old female patient presented with abdominal discomfort, constipation, weight loss and occasional vomiting for the past 5 months.

Imaging Findings

Axial CECT abdomen (Fig. 1) showed a sausage-shaped mass with invagination of proximal ascending colon into its distal part. There was thickening of the ascending colon (~ 22mm) which was the lead point causing intussusception. Cross-sectional image of the mid-portion of intussusception (Fig. 2) illustrated typical bowel within bowel appearance or target sign. No hepatic or bone metastasis was noted.

Discussion

Telescoping of proximal segment of gut into distal segment is called intussusception. Proximal segment (prolapsing part) is called intussusceptum while the distal segment of bowel receiving the intussusceptum is called the intussuscipiens. Any intraluminal lesion (leading point) is able to trigger an intraluminal invagination finally causing an intussusception. Subsequent peristaltic bowel activity produces an area of sequence constriction and relaxation, thus telescoping the leading point through the distal bowel lumen which can cause bowel obstruction and compromise of mesenteric blood flow, with resultant ischaemia of the bowel wall. Intussusceptions can also occur without a lead point which are usually transient [1, 2].

Intussusceptions are classified according to location (enteroenteric, ileocolic, ileocaecal, or colocolic) and cause (benign, malignant, or idiopathic). Enterocolic intussusception is the most common type [1, 3]. Intussusception is commonly seen in children (95%). Adult intussusceptions are rare accounting for 5% of all intussusceptions and 1% of all bowel obstructions. The mean age is 50 years. A definable lead point is seen in 70-90% of adult intussusceptions, as opposed to paediatric intussusception, which is idiopathic in 90% of cases. Approximately 80% are due to benign lesions (e.g. adhesion, lymphoid hyperplasia, lipoma, leiomyoma, Meckel’s diverticulum, gastrointestinal stromal tumor, Peutz-Jegher adenoma) in small bowel intussusception. In contrast, the colon is more likely (60%) to have malignant lesion as the cause of intussusception where adenocarcinoma accounts for two thirds of cases and malignant lymphoma for one third of cases [2, 4-6].

The most common symptoms of intussusception are abdominal pain, nausea, and vomiting; less frequent symptoms are melena, weight loss, fever, and constipation.

In our case ultrasound showed bowel within bowel appearance in right lumbar region (target sign). However, the scan was suboptimal due to gaseous distension of the abdomen. Contrast enhanced computed tomography was done which revealed the site of intussusception (colocolic) and the lead point. The patient underwent right hemicolectomy. Histopathological examination of the tumour revealed high-grade mucinous adenocarcinoma.

Intussusception in adults is a rare entity and diagnosis may be challenging because of nonspecific symptoms as in our case. A high index of suspicion is required to diagnose a case of colocolic intussusception in an adult. This is particularly important because an underlying malignancy may first present as an intussusception. Abdominal CT is a good modality in distinguishing between lead point and non-lead point intussusception and helps in timely management [1, 2, 5]. Non-lead point intussusceptions usually don't require surgery.

Differential Diagnosis List

Final Diagnosis

Colocolic intussusception (colonic mass as lead point)

URL:	https://www.eurorad.org/case/13518
DOI:	10.1594/EURORAD/CASE.13518
ISSN:	1563-4086