Peritonitis chronica fibrosa incapsulata

Encapsulating peritoneal sclerosis is a rare benign cause of acute or subacute small bowel obstruction. It is characterized by total or partial encasement of the small bowel within a thick fibrocollagenous membrane.

Terminology

The condition was originally termed abdominal cocoon. The condition is popularly known as sclerosing encapsulating peritonitis, however, this is somewhat of a misnomer as inflammation is not always present . It has also been known as sclerosing peritonitis, encapsulating peritonitis, and peritonitis chronica fibrosa incapsulata.

Epidemiology

Encapsulating peritoneal sclerosis can occur at any age, with reports ranging from 2-day neonate to 82 years .

Clinical presentation

The presentation is non-specific and patients may present with vomiting, abdominal pain and/or a subacute bowel obstruction .

Pathology

It can be idiopathic or secondary due to:

Various abdominal disorders such as tuberculosis, sarcoidosis, familial Mediterranean fever, gastrointestinal malignancy, ovarian carcinoma , protein S deficiency, liver transplantation, fibrogenic foreign material, and luteinised ovarian thecomas are the other rare causes.

Radiographic features

Plain radiograph

Abdominal radiographic appearances are nonspecific and may be normal or may show:

  • gas-fluid levels similar to those in patients with any other cause of small-bowel obstruction
  • the wall of the "cocoon" may calcify
Ultrasound
  • clumped bowel loops
  • trilaminar appearance of a hyperechoic membrane, hypoechoic bowel wall and hyperechoic bowel contents
  • ascites may be present
CT

In the appropriate clinical setting, recognition of the entire dilated small bowel at the center of the abdomen and encased within a thick fibrocollagenous membrane, as though it were in a cocoon, is diagnostic of sclerosing encapsulating peritonitis. The other imaging findings may include:

  • enhancing peritoneum, thickened >2 mm
  • signs of small intestinal obstruction
  • fixation of intestinal loops
  • ascites or localized fluid collections (especially interbowel)
  • bowel wall thickening
  • peritoneal or mural calcification
  • calcified and/or reactive adenopathy
MRI

MRI will demonstrate the same features as CT, although it may better discriminate between thickened bowel and the peritoneal membrane than CT .

Differential diagnosis

Encapsulating peritoneal sclerosis may be confused with congenital peritoneal encapsulation, which is characterized by a thin accessory peritoneal sac surrounding the small bowel.

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