Colocolic intussusception presenting as gastrointestinal bleeding

Clinical History

A 47 year old female presented to the emergency department with hematochezia and lower abdominal pain which started 24-hours ago. She denied previous bleeding, changes in the bowel habits, fever and weight loss. After being admitted to further investigation she progressed to bowel obstruction. Endoscopy revealed an odd-shaped mass within the sigmoid (fig1).

Imaging Findings

CT revealed a doughnut/target-like (fig2) image continuous with colonic lumen at the sigmoid level. This image was related with an intussusception and the highly heterogeneous and enhancing appearance of the intussusceptum suggested an underlying malignant neoplasm as a lead point (fig3). There was cecal distention and impactation of feces proximal to the lesion, related to the obstruction. Between the intussusceptum and the intussuscipiens there was a fatty layer that represented the mesosigmoid containing vessels and suspicious lymph nodes (fig2, 3).

There were no extraluminal air bubbles nor signs of ischemia, and no sign of dissemination to other organs nor structures.

Clinical follow up:

The patient underwent sigmoidectomy and 18 lymph nodes were removed. An underlying adenocarcinoma was diagnosed, invading all layers except the serosa - the final staging was a pT3N0M0, as none of the lymph nodes were invaded.

The mid-term follow up was favourable, with no evidence of disease nor complications.

Discussion

Intussusception is defined as telescoping of a part of the gastrointestinal tract into an adjacent one [1]. Although this is a relatively common cause of an acute abdomen in children, it is much less common in adults (only 5% of all intussusceptions [2]). Also in contrast to intussusceptions in children, most are idiopathic, in the adult population an underlying lesion is found in 70-90% of the cases [3] - almost half associated with malignancy [2].

Intussusceptions can be classified according to the involved segments (enteroenteric, colocolic etc.), cause (benign, malignant, or idiopathic) and also further classified by whether a lead-point can be demonstrated [3] (usually no lead point can be shown in children as these are thought to be related to enlarged lymphoid tissue, following an infection).

Clinical findings are often atypical but there are often prior symptoms that suggest partial intestinal obstruction (like crampy abdominal pain, nausea, constipation and vomiting)[3]. Symptoms may also be related to a neoplastic process (e.g. weight loss)[3].

CT has proved to be the most useful imaging method [2]. The imaging appearance of an intussusception depends upon the presence of a lead point, the morphology of the lead mass, the degree mural edema and the amount of invaginated mesenteric fat [3] and lymph nodes (fig2 - think of the "smiley face" as a memory hook). An early intussusception may have the classical transverse doughnut/target-like appearance, with the intussusceptum is the center and the edematous intussuscipiens at the periphery (fig2, 3), forming the external ring or a “sandwich/pseudo-kidney sign” (fig 4 and 5 respectively) when imaged in longitudinal sections [2, 4]. As the mural oedema increases, there is more layering and the cross-sectional diameter increases. Finally, with the abnormal blood flow to the mesenteric vessels or significant inflammation, mural damage may lead to a sausaged shaped/amorphous mass-appearing lesion, with an associated proximal obstruction [3, 4].

Colo-colic are the rarest type intussuspections [4] but differentiation of the lead mass from bowel wall oedema at CT is generally easier than in small bowel intussusception due to the greater caliber of the colon.

Lipomas are the most common benign cause of colocolic intussusception in adults and can be diagnosed due to their typical fat attenuation [3] - in the preseted case this hypothesis was likely excluded since no fat was detected.

Adenocarcinoma of the colon is the most common malignant neoplasm associated with colonic intussusception [3] and, as in the demonstrated case, it is not necessarily related with advanced disease.

Differential Diagnosis List

Final Diagnosis

Colo-colic intussuspection related to an underlying Adenocarcinoma of the Colon

URL:	https://www.eurorad.org/case/12913
DOI:	10.1594/EURORAD/CASE.12913
ISSN:	1563-4086