Intussusceptions of the small bowel are usually caused by benign neoplasms5 6
(lipoma, leiomyoma, haemangioma, neurofibroma), adhesions, Meckel's diverticulum, lymphoid hyperplasia, trauma, coeliac disease, intestinal duplication or Henoch–Schonlein purpura. Malignant lesions causing intussusception of the small intestine account for about 15% of the cases2
and are more often metastatic (frequently melanoma7
). Idiopathic intussusception occurs in about 20% of all small-bowel intussusceptions.
In adults, it is important to differentiate between small bowel and colonic intussusception; in fact, in 63% of cases of small-bowel intussusceptions, a benign underlying lesion can be found, whereas in 58% of cases of large-bowel intussusceptions, a malignant aetiology has to be expected.5
A lipoma of the gastrointestinal system, found post mortem in 0.2%, is a benign tumour composed of mature lipocytes.8
Only 20–25% are found in the small bowel.9
CT-scan diagnosis of intussusception is usually characteristic: a soft tissue mass containing outer intussusceptions and an inner intussusceptum.10
The lipoma appears on CT scan as a round, homogeneous mass with fat attenuation values, within the lumen of the intussusceptions. When a malignant lesion is suspected, CT scan might also be useful for staging. It can identify bowel dilatation, free fluid, metastases or lymphadenopathy.11 12
In middle-aged patients presenting with recurrent abdominal symptoms, unusual causes of intestinal obstruction should be considered, but a careful and thorough evaluation of the CT scan findings should warrant to avoid missed lesions. Finally, during surgery for bowel obstruction, if the bowel distal to the lesion is not collapsed and it does not distend up, then the area treated may not be the true point of obstruction.
- In middle-aged patients presenting with recurrent abdominal symptoms, unusual causes of intestinal obstruction should be considered.
- If the plain abdominal x-ray shows air-fluid levels and grossly distended bowel loops, the level and possible site of obstruction must be assessed (ie, small bowel or large bowel). A CT scan with double or triple contrast should be part of the diagnostic workup if water-soluble contrast follow-through or a contrast enema are not feasible or are inconclusive.
- A careful and thorough evaluation of the CT scan by the radiologist should take place to ensure lesions are not missed.
- The most radiologically evident or outstanding finding should not sidetrack the radiological diagnosis.
- The surgeon should not neglect to perform a careful and thorough intraoperative exploration and palpation of the gut, from the upper to the lower parts, even when a lesion is found that can explain the obstruction present. The finding of distended bowel distally to the lesion suspected of being the cause of the obstruction should suggest the possible presence of a further concomitant, obstructing, lesion in the distal bowel.