Case of the Month: February, 2011 Page 2

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Diagnosis: Epiploic Appendagitis.

Two axial CT scans of the lower abdomen show the classic findings of an oval, fat-containing mass anterior to the ascending colon with surrounding inflammatory fat stranding.  There is a characteristic dense focus within the fatty mass which may represent a thrombosed vessel or hemorrhage.

Discussion:

Etiology

• Acute inflammation or infarction of epiploic appendages
  • Peritoneal outpouchings originating from the serosal surface of colon, containing blood vessels and fat
• May be caused by venous occlusion
• Secondary epiploic appendagitis is caused by inflammation of an adjacent structure
• Occurs most often in men in 4th and 5th decade

Clinical Findings

• Findings resemble acute diverticulitis or appendicitis
• Usually left lower quadrant abdominal pain
• Fever is usually absent or mild , and white blood cell count is usually normal
• Vigorous exercise and obesity have been postulated as facilitating torsion of the appendage

Imaging Findings

• On CT:
  • 1.5-3.5 cm fat density lesion with surrounding inflammatory changes
  • Characteristic central high density focus within fat (54%)
    • Probably representing thrombosed blood vessel
  • Occasionally, fat necrosis may lead to calcification of the appendage
• On ultrasound:
  • Non-compressible echogenic ovoid mass at point of tenderness with hypoechoic ring (swelling of serosa)
• More common in LLQ with majority (57%) occurring at the rectosigmoid junction
• Changes resolve within 6 months

Differential Diagnosis

• Diverticulitis
• Mesenteric panniculitis
• Appendicitis
• Trauma
• Omental infarction
• Ulcerative colitis
• Neoplasm, i.e. liposarcoma

Treatment

• Conservative treatment with pain medication
• Non-surgical

Complications

• Rare but include adhesions, obstruction, peritonitis, abscess formation

Prognosis

• Benign and self-limited disease, should result in spontaneous and complete resolution within one week.