Presentation
Abdominal pain and vomiting.
Patient Data
CT shows mildly dilated and clustered small bowel loops (Jejunal and ileal loops) giving the appearance of a cocoon. The small bowel loops are encapsulated with a thin layer of peritoneum. The terminal ileum and large bowel appear normal. No ascites seen.
Small nodular calcification in the liver, likely old healed granuloma.
The rest of the abdomen appears unremarkable.
Case Discussion
The above CT findings could be due to congenital peritoneal encapsulation with small bowel obstruction. The close differential diagnosis includes abdominal cocoon, encapsulating peritoneal sclerosis and internal hernia.
Acquired peritoneal encapsulation is secondary to the formation of a thick fibrotic membrane encasing the bowel. It includes abdominal cocoon (idiopathic) and encapsulating peritoneal sclerosis (secondary to underlying disease). The common cause of encapsulating peritoneal sclerosis includes- ambulatory peritoneal dialysis, tuberculosis, and ventriculoperitoneal shunt. In both acquired conditions, the formed membrane is a thick fibrotic membrane and tends to have adhesions with the peritoneal membrane with or without calcifications.
In congenital peritoneal encapsulation (CPE), the encapsulating membrane encasing the bowel will be thin without any evidence of calcification. It shows identical histologically to the peritoneum.
Internal hernias such as paraduodenal hernias were thought less likely as the appearance was not typical and by the relationship of the sac anterior to the stretched mesenteric vessels and descending colon. Transmesenteric internal hernia may look like congenital peritoneal encapsulation on imaging but a thin encapsulating membrane is usually absent.
Co-author: Dr. Tanu, MD (Radiodiagnosis).
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