Epiploic appendices are small pouches of fat covered by peritoneum that hang from the colon. Often discovered incidentally on imaging, they are typically harmless but can become inflamed in a condition known as epiploic appendicitis.
Although similar in name to the epiploic foramen, these appendages are distinct structures that rarely cause serious disease. Understanding their appearance, complications, and management helps clinicians avoid unnecessary procedures.
| Structure | Location | Typical Size | Clinical Relevance |
|---|---|---|---|
| Epiploic Appendices | Along the colon, especially the sigmoid and descending colon | 2 to 5 mm, up to 2 cm | Can undergo torsion, infarction, and mimic diverticulitis |
| Epiploic Foramen | Posterior to the hepatoduodenal ligament | Several centimeters in adults | Portal vein or hepatic artery compression risk |
| Mesenteric Fat | Mesentery between bowel loops | Variable, nodular or diffuse | Associated with vasculitis, ischemia, and infection |
| Omental Appendices | Along the colon, similar distribution | Small fatty nodules | Low clinical significance, often incidental |
Imaging Features on CT and Ultrasound
Typical Appearance on Cross-sectional Imaging
On CT scans, epiploic appendices appear as well-circumscribed, oval fat-density masses with a central dot-like enhancing vessel. They commonly enhance on contrast-enhanced sequences, which helps distinguish them from phlegmon or abscess. Their location along the colon and absence of bowel wall thickening are key radiographic clues.
Differentiating from Diverticulitis and Appendicitis
Inflammation of an epiploic appendix can mimic acute diverticulitis or appendicitis due to localized pain, tenderness, and possible surrounding stranding on imaging. However, epiploic appendicitis typically lacks colonic wall thickening or free fluid, which aids in accurate identification. Recognizing these features reduces the risk of misdiagnosis and inappropriate surgery.
Pathophysiology of Epiploic Appendiceal Torsion
Mechanism of Torsion and Infarction
Each epiploic appendix is attached by a small mesentery containing a single vessel. Twisting of this pedicle can compromise blood flow, leading to infarction. The resulting ischemic fat becomes edematous and hyperemic, causing acute, often severe, localized abdominal pain. This process is responsible for epiploic appendicitis.
Risk Factors and Predisposing Conditions
While torsion can occur at any age, it is more common in middle-aged adults. Contributing factors include colonic motility disorders, vigorous exercise, and sudden changes in intra-abdominal pressure. Obesity and a high-fat diet may also increase the likelihood of peduncle torsion by enlarging the appendices.
Clinical Presentation and Diagnostic Evaluation
Symptoms and Physical Examination Findings
Patients typically present with acute, localized abdominal pain that may be mistaken for surgical abdomen. There may be mild fever, nausea, or rebound tenderness over the affected area. Bowel habits are often unchanged, which can help differentiate this condition from inflammatory bowel disease or obstruction.
Role of Imaging and Laboratory Studies
Laboratory tests often show mild leukocytosis but are otherwise non-specific. Ultrasound may reveal a hyperechoic mass with a central vessel, while CT provides definitive diagnosis by demonstrating fat density plus a central enhancing dot. Awareness of these patterns guides appropriate conservative management.
Key Takeaways and Practical Recommendations
- Recognize epiploic appendices as normal fatty structures along the colon.
- Remember that epiploic appendicitis can mimic diverticulitis or appendicitis on clinical and imaging grounds.
- Use CT findings, including fat density with central enhancement, to confirm the diagnosis.
- Prefer conservative management in confirmed cases, reserving surgery for atypical presentations.
- Educate patients that incidental detection of these structures usually requires no intervention.
FAQ
Reader questions
What exactly are epiploic appendices and are they normal structures?
Yes, epiploic appendices are normal, small fatty projections of the visceral peritoneum found along much of the colon. They are considered anatomical variants present in most adults and usually cause no symptoms.
Can inflammation of an epiploic appendix lead to serious complications?
Infection or torsion of an epiploic appendix, known as epiploic appendicitis, can cause severe pain and localized peritonitis but rarely leads to perforation or sepsis. With proper diagnosis, complications are uncommon and typically managed conservatively.
How is epiploic appendiceal torsion distinguished from acute diverticulitis on imaging?
Imaging shows a well-defined fat-density lesion with a central vessel in epiploic appendiceal torsion, whereas diverticulitis features colonic wall thickening, diverticula, and often surrounding inflammation or abscess. The absence of colonic mucosal involvement helps confirm the former.
Is surgical intervention ever necessary for these structures?
Most cases resolve with rest, analgesia, and observation. Surgery is reserved for diagnostic uncertainty, persistent severe symptoms, or rare complications such as infarction with secondary infection. Conservative management remains the standard approach.