Yet another case of abdominal pain?

Correct answer: C.

Discussion

The yellow arrows on figure 3 indicate the presence of small bowel intussusceptions involving different segments of ileal loop in the case patient.

Intussusception is a serious condition in which part of the intestine slides into an adjacent part of the intestine. This ‘telescoping’ often blocks food or fluid from passing through the intestine. Intussusception also cuts off the blood supply to the part of the intestine that’s affected, which can lead to a tear in the bowel (perforation), infection and death of bowel tissue.¹

Intussusception is the most frequent cause of bowel obstruction in paediatric patients;²however, it may occur in adults as the result of an underlying medical condition, such as a tumour, which may act as lead point, dragging part of the bowel into the neighbouring segment.³

There are several medical conditions/situations known to contribute to intussusception in adults:

• Congenital abnormalities (e.g. Meckel diverticulum, ectopic pancreas, duplication cyst)
• A polyp or tumour
• Scar-like tissue (adhesions) in the intestine 
• Weight-loss surgery (gastric bypass) or other surgery on the gastrointestinal tract
• Gastrointestinal inflammation caused by disease (e.g. Crohn's disease)

When intussusception occurs in adults, the most frequent symptom is abdominal pain that comes and goes. Nausea and vomiting may also occur. People sometimes have symptoms for weeks before seeking medical attention. A repeat CT scan was performed, and the findings are shown in figure 4.

Correct answer: D.

Discussion

Congenital abnormalities are more likely in young patients and a single area of the bowel is usually involved. 17–30% of small bowel tumours are lymphomas, but they are solitary lesions or involve a single portion of the small bowel (5–20 cm). Furthermore, on imaging they are observed to have the same thickness as the bowel wall. A polyp syndrome is unlikely in this case because FAP involves the colon, while Peutz-Jeghers syndrome involves the small bowel, but melanosis is usually present as well.  Small intestinal metastases are rare and originate mostly from kidney carcinoma or melanoma, but they were suspected to be the cause of the intussusception in the case patient because metastases had been noticed in the liver (figure 5).

Biopsy samples were taken from the hepatic nodules and the duodenum was resected, and the findings confirmed metastases of an epithelioid-cell-type melanoma to the enteric wall, liver and peritoneum. The case patient subsequently developed neurological manifestations (figure 6). 

Metastatic melanoma affects the small bowel more often than the colon.⁴ Unfortunately, the disease has a late clinical onset and diagnosis is often made only when complications, such as bleeding, obstruction or perforation, occur.  However, there are only few reports of small bowel intussusception caused by melanoma.⁵ CT is important for diagnosis and staging, followed by histology.^6,7 Surgery is often required as is palliative treatment to manage complications (+/- adjuvant chemo/radiotherapy).⁸