Epiploic appendagitis

Clinical History

A 48-year-old man presents with a four weeks history of increasing lower abdominal pain and change in bowel habit. History of recent steroid intake for pulmonary eosinophilia. O/E vitals stable, tenderness and guarding noted in the hypogastrium and left iliac fossa. Lab: neutrophilic leucocytosis (15,000) and mildly raised CRP (15mg/L).

Imaging Findings

Chest and abdominal radiographs done in the emergency department did not show any abnormality.

Contrast-enhanced CT of the abdomen and pelvis performed the next day demonstrated a rounded area of inflammatory change, with a fatty central core in close relation to the anterolateral wall of the proximal sigmoid colon and a thickened adjacent visceral peritoneal lining. A central high density was noted in the fatty core.

The colonic wall was not thickened or inflamed. There was no evidence of diverticular disease of the colon. The appendix was visualised in its usual position and appeared normal.

No other abnormalities such as free gas or fluid were identified.

The imaging findings were characteristic of epiploic appendagitis. The patient recovered completely on conservative management with analgesia.

Discussion

Epiploic appendagitis (EA) is an inflammatory process involving the appendices epiploicae and is a benign and self-limiting condition. It is an uncommon cause of abdominal pain and has only recently been widely recognised with the increasing usage of cross sectional imaging [1, 2]. It is commonly diagnosed on CT.

Appendices epiploicae are fatty outpouchings from the serosal surface of the colon originating parallel to the longitudinal muscle band of the colon, taenia coli. The pathophysiology is thought to be venous occlusion from torsion although spontaneous thrombosis of the draining appendageal vein has been described as an uncommon cause.
The common location is rectosigmoid junction (57%), ileocecal region (26%), ascending colon (9%), transverse colon (6%), and descending colon (2%) [3].

The usual clinical presentation is with left-sided lower abdominal pain. Depending on the location, it can mimic acute diverticulitis, appendicitis or other causes of abdominal pain. Because various acute abdominal conditions require urgent surgical intervention, a rapid diagnosis is imperative. Hence, urgent imaging is necessary to make a definitive diagnosis [4].

The diagnosis of EA primarly relies on CT although US and MRI have been occasionally used.

On US, the inflamed epiploic appendage appears as a solid echogenic non-compressible finger-like projection arising from the colonic wall [5] but the sensitivity varies widely depending on the operator expertise.

On MRI, the involved epiploic appendage is hyperintense on T1 (slightly less intense than normal peritoneal fat). The central draining vein usually has low signal on both T1-weighted and T2-weighted imaging. Marked enhancement is noted on post-contrast images [6].

The typical CT findings of EA include an ovoid pericolic mass with fat density but higher in attenuation than uninvolved fat, surrounded by inflammatory changes and abutting the anterior colonic wall. A surrounding hyperdense ring represents an inflamed peritoneal covering of the appendage. A hyperdense central "dot" is present in approximately 50% of cases and represents a thrombosed central vein [1].

Differentiation from diverticular disease is by the absence of diverticula, mesocolic thickening and engorged segmental vessels. Furthermore, complications such as fistulae and fluid collections are absent. Appendicitis can be ruled out by visualisation of the normal appendix.

Differentiation from omental infarction can be difficult but the involved area is larger compared to EA, more ill-defined and without the hyperdense ring, and located on the right side of the abdomen.

Differential Diagnosis List

Final Diagnosis

Primary epiploic appendagitis

URL:	https://www.eurorad.org/case/9136
DOI:	10.1594/EURORAD/CASE.9136
ISSN:	1563-4086