Clinical History
A 63-year-old woman with unremarkable past medical history was referred to Radiology department to investigate recurrent episodes of crampy abdominal pain and significant weight loss (8 kg) during the past two months. Physical examination failed to reveal abnormal or acute findings. Laboratory tests disclosed anaemia (9.6 g/dl haemoglobin).
Imaging Findings
Recent colonoscopy and upper digestive endoscopy yielded normal findings.
Suggested by the attending radiologist to comprehensively investigate the small bowel and other abdominal viscera, multidetector CT-enterography (Fig.1) was performed following oral intake of 750 mL nonabsorbable water-attenuating polyethylene-glycol solution.
As the sole abnormality, in the pelvis a right paramedian ileal lesion was detected, characterised by “target” and “sausage-shaped” appearances in perpendicular and parallel planes to its major axis respectively, suggesting enteric intussusception.
Focused reformatted images effectively depicted the entire extent of the abnormality and the presence of a 5-cm roundish, well-demarcated solid mass at its head.
Laparotomic surgery and gross pathology findings confirmed ileo-ileal intussusception caused by a yellow, circumscribed solid luminal productive mass, treated by segmental bowel resection. Postoperative course was uneventful.
Histopathology of the lesion reported vascular, mixoid and fibroblastic tissue stroma with neutrophil, histiocyte, and eosinophil infiltration, without signs of neoplasia, consistent with inflammatory fibroid polyp (Vanek’s tumour).
Discussion
Defined as “telescoping” of a proximal gastrointestinal (GI) segment into the adjacent distal bowel, intussusception represents an uncommon (1-5% of cases) cause of small bowel (SB) obstruction in adults. Clinical manifestations of SB intussusception include chronic colicky pain, intermittent or acute obstruction. Differently from paediatric patients, the majority (70-90%) of adult intussusception cases occur secondary to mural or intraluminal pathologic changes acting as lead point [1-4].
Although very rare, the inflammatory fibroid polyp (IFP, Vanek’s tumour) is recognised as a possible cause of SB intussusception. A localised, non-neoplastic lesion whose aetiology and pathogenesis remain unknown, IFP may develop from the submucosa throughout the GI tract, most commonly in the gastric antrum (70% of cases). Pathologically IFP are solitary or sessile, non-encapsulated masses usually 2-5 cm in size, mainly composed of fibrous and oedematous stroma containing abundant blood vessels, inflammatory infiltrate with eosinophilic predominance. IFP occurs in both sexes, with peak incidence in the sixth decade. Clinical manifestations vary according to lesion site, including asymptomatic incidentally detected cases, chronic relapsing pain, lower GI bleeding, or acute intestinal obstruction. The less frequent (18% of cases) ileal involvement is often complicated by episodes of SB obstruction from intussusception [1-3, 5, 6].
Whereas plain radiographs are usually performed to confirm and grade suspected bowel obstruction, currently multidetector CT (MDCT) is the preferred technique to investigate site and underlying causes, in order to allow correct therapeutic planning. Usefully complemented with multiplanar reformations, MDCT shows uncomplicated intussusception with the characteristic “target” appearance in perpendicular planes to the main intestinal axis, due to outer and intraluminal mural soft tissue separated by invaginated mesenteric fat and vessels. With disease progression, a longitudinal “sausage-shaped” appearance with alternating low and high attenuation representing mesenteric fat and bowel wall appears. Although intussusceptions are increasingly and confidently detected at imaging, considerable overlap exists at MDCT between intussusceptions with and without lead point [4, 7].
Poorly reported in radiological literature, the rare IFP has no characteristic imaging findings, and should be considered –along with gastrointestinal stromal tumours- among causes of secondary SB intussusception in adults, particularly when a solitary expansile lesion is appreciated at the intussusception head point. Despite absent recurrence and malignant potential, surgical resection is the treatment of choice, necessary to prevent bowel ischaemia and perforation, and to provide histopathological confirmation [1-3, 5, 6].
Differential Diagnosis List
Ileo-ileal intussusception caused by small bowel (Vanek's) inflammatory fibroid polyp.
Idiopathic / transient small bowel intussusception
Gastrointestinal stromal tumour (GIST)
Ileal carcinoma
Ileal lymphoma
Ileal lipoma
Ileal leiomyoma
Ileal neurofibroma
Meckel’s diverticulum
Celiac disease
Crohn’s disease
Intestinal tuberculosis
Obstruction caused by adhesions
Final Diagnosis
Ileo-ileal intussusception caused by small bowel (Vanek's) inflammatory fibroid polyp.
