Epiploic appendagitis

Epiploic appendagitis also called appendicitis epiploica, hemorrhagic epiploitis, epiplopericolitis or appendagitis, is a rare benign (harmless) self-limiting inflammatory process of the colonic epiploic appendices caused by an ischemic infarction of an epiploic appendage due to torsion (twisting) or spontaneous thrombosis of the epiploic appendage central draining vein ¹. The risk of recurrence is low and complications are even rarer ². Epiploic appendages are normal small fat-filled sacs on the anti-mesenteric surface of the colon. Epiploic appendagitis is a benign and self-limited condition ³. Unlike its mimics, epiploic appendagitis is, generally, a self-limiting local inflammation and can be treated with anti-inflammatory medication ⁴. For these reasons, it is very important for clinicians to consider epiploic appendagitis as a cause for abdominal pain since inaccurate diagnosis can lead to prolonged hospital stay, antibiotic therapy, and surgical interventions ⁵. Today, ultrasound (US) and CT scan play a crucial role in diagnosis of this epiploic appendagitis ⁶. The normal epiploic appendages are undetectable on computed tomography (CT) images due to the overlapping in density with the surrounding peritoneal and omental fat, while they can be noted when they are inflamed and/or outlined by ascites ⁷.

Epiploic appendagitis is usually diagnosed by CT scanning and has become more widely recognized given today’s higher resolution scanners. Imaging findings include the presence of an oval lesion with fat-attenuation surrounded by a thin hyperdense rim on CT (“hyperattenuating ring sign”) abutting anteriorly the large bowel, usually associated with inflammation of the adjacent mesentery ⁸. A central high-attenuation focus within the fatty lesion (“central dot sign”) can sometimes be observed and is indicative of a central thrombosed vein within the inflamed epiploic appendage ⁸. Rarely, epiploic appendagitis may be located within a hernia sac or attached to the vermiform appendix. Chronically infarcted epiploic appendage may detach, appearing as an intraperitoneal loose calcified body in the abdominal cavity ⁸.

The most common sites of development of epiploic appendagitis are the rectosigmoid (57%) and the ileocecum (26%); rarer sites are the ascending (9%), transverse (6%), and descending colon (2%) ⁵.

Epiploic appendagitis is a rare condition with an incidence of 8.8 per 1 million people and it is usually a diagnosis by exclusion ⁹. Epiploic appendagitis may occur at any age. Two retrospective studies reported that men (70%) were affected more than women with an age range of 26 to 75 years ⁶. The average patient is about 40 years old and develops acute abdominal pain which may be left-sided, right, or central. The pain is sharp and stabbing and may be associated with nausea or vomiting. Fever is usually absent. The symptoms from epiploic appendagitis often mimic acute appendicitis, diverticulitis, or cholecystitis. Initial lab studies are usually normal. Typically, a CT scan is ordered to help exclude more serious or surgical problems (above) and the inflammatory changes of epiploic appendagitis are seen coincidentally. epiploic appendagitis follows a benign, self-limiting course and may be treated with analgesics and expectant observation. The usual time course is about one week. A correct diagnosis is important to avoid unnecessary surgical or medical intervention.

At clinical examination, patients usually describe a localized, strong, nonmigratory, sharp pain which usually started after a specific physical movement of their body, like postprandial exercise. An abdominal tenderness is present in all patients. There is a lack of fever, vomiting or leukocytic response ⁶. Diagnosis of epiploic appendagitis is made challenging by the lack of pathognomonic clinical features and should therefore be considered as a potential diagnosis by exclusion. With diverticulitis and appendicitis being the most important causes of lower abdominal pain, they are the most frequent clinical diagnosis before diagnostic imaging or diagnostic laparoscopy. The pain usually is located on the left or right lower abdominal quadrant ⁶.

Epiploic appendagitis key points

• Epiploic appendagitis is a rare entity causing acute abdominal pain, due to a benign, self-limited inflammation of the epiploic appendages.
• Epiploic appendagitis is a clinical mimicker of other acute abdomen causes, including acute diverticulitis and appendicitis.
• Imaging features of epiploic appendagitis include fat-density ovoid lesion, “hyperattenuating ring sign,” mild bowel wall thickening, and “central dot sign.”

Figure 1. Epiploic appendages

Epiploic appendages anatomy

Epiploic appendages are small outpouchings of fat-filled, serosa-covered structures present on the external surface of the colon projecting into the peritoneal cavity. Each appendage encloses small branches of the circular artery (one or two arterioles) and a single vein that supply the corresponding segment of the colon ¹⁰. Subserosal lymphatic channels either terminate in a lymph node within an appendage or loop through its base en route to mesenteric nodes.

On average, the adult colon has approximately 50 to 100 appendages ¹¹. Epiploic appendages occur all along the entire colon but are more abundant and larger in the transverse and sigmoid colon. They are usually rudimentary at the base of the appendix ¹². The epiploic appendages vary considerably in size, shape, and contour. Most epiploic appendages are 1 to 2 cm thick and 2 to 5 cm long, although they are occasionally up to 15 cm ¹³. For unclear reasons, they are largest and most prominent in obese persons and in those who have recently lost weight ¹⁴. Although the exact role of epiploic appendages is not known, they are presumed to serve a protective and defensive mechanism similar to that offered by the greater omentum and may have a role in colonic absorption ¹⁴. Epiploic appendages may also act as a cushion, protecting colonic blood supply during peristalsis ¹⁵.

Epiploic appendagitis causes

Epiploic appendagitis is caused by a spontaneous torsion or twisiting causing obstruction of blood flow within the tissue and then ischemia up to a gangrenous necrosis of the epiploic appendage or by primary thrombosis of the draining vein and inflammation ¹¹. Epiploic appendagitis may also be secondary to other local inflammatory processes affecting adjacent organs, particularly in case of diverticulitis, appendicitis, pancreatitis, or cholecystitis ¹⁶. Obesity and rapid weight loss are described as potential risk factors for the development of epiploic appendagitis ¹⁷.

Epiploic appendagitis symptoms

Epiploic appendagitis clinical presentation may vary among patients. Epiploic appendagitis clinical presentation is typically characterized by acute or subacute abdominal pain, in most cases (60–80%) in the left lower quadrant, but it can also be localized in the right lower quadrant ¹⁸ miming a varied number of diseases such as appendicitis, diverticulitis, acute cholecystitis, and omental infarction ¹⁹. Patients may also report postprandial fullness, swelling, vomiting, early satiety, diarrhea, and rarely mild fever ²⁰.

Epiploic appendagitis is often an underestimated and overlooked mimicker, easily misdiagnosed with other causes of abdominal pain requiring urgent care or surgical evaluation in emergency department, particularly acute diverticulitis (left iliac pain) or acute appendicitis (right iliac pain) ²¹.

On physical examination, patients complain of focal non-migratory abdominal pain in the lower abdominal quadrants (left more commonly than right), not exacerbated by physical movement, without significant guarding or rigidity, and in the absence of a palpable mass ²⁰. The pain is typically circumscribed and the patient may often point his finger on the place where the lesion is situated.

Epiploic appendagitis complications

Complications of primary epiploic appendagitis have been occasionally reported. The inflammatory process may rarely cause adhesions and lead to small bowel obstruction and thus required surgical treatment ²². Epiploic appendages are not in continuity with the fecal content, indeed pyogenic abscesses are not a typical complication ²³. In case of CT evidence of intra-abdominal abscess, the diagnosis of epiploic appendagitis secondary to complicated diverticulitis should be considered ²⁴.

Epiploic appendagitis diagnosis

Imaging studies

The clinical diagnosis of epiploic appendagitis is challenging due to the lack of pathognomonic clinical signs or laboratory markers ⁸. Currently, thanks to the increased use of ultrasound (US) and CT scan in the evaluation of acute abdominal pain, most cases of epiploic appendagitis are diagnosed using CT (preferred) and ultrasound scan ²⁵. Instead, Magnetic Resonance Imaging (MRI) is rarely used for diagnosis. Abdominopelvic ultrasound scan and CT examinations do not allow seeing the normal epiploic appendices, unless there is surrounding intraperitoneal fluid ²⁶. In cases of acute epiploic appendagitis, ultrasound evaluation shows, in the patient’s area of maximal tenderness, the presence of a small (2-4 cm in maximal diameter) rounded or ovoid, noncompressible, and hyperechoic mass adherent to the colonic wall, without internal blood flow on color or power Doppler studies, frequently surrounded by a subtle hypoechoic line ²⁷. The typical CT findings in cases of acute epiploic appendagitis include the presence of rounded or ovoid fat-density mass adjacent to the colonic wall, usually less than 5 cm in diameter (typical diameter range: 1.5–3.5 cm) ²⁸, the “hyperattenuating/hyperdense ring sign” ²⁹, a hyperdense enhancing rim (thickness of 1-3 mm) surrounding the lesion, and the perilesional inflammatory fat stranding ²⁷. A pathognomonic CT finding of epiploic appendagitis is the “central dot sign”, characterized by a central, ill-defined round area of high attenuation within the fat-density mass ³⁰. This sign is also known as the “dense central vessel sign” due to engorged or thrombosed vessel within the inflamed epiploic appendage ³¹. Although the presence of this area of high attenuation is pathognomonic, its absence does not preclude a diagnosis of acute epiploic appendagitis ³².

MR may show a small oval mass with a signal intensity similar to the fat. Contrast-enhanced T1-weighted MRI images show also an enhancing rim around the oval fatty mass ¹⁹.

The wall of the colon may show associated reactive thickening ²⁷.

Chronically, a calcification can develop within the infarcted appendage epiploica and may detach to form an intraperitoneal loose body (peritoneal “mice”) ³³. Rarely, appendagitis may be located in the hernia sac ²⁷ or involve the vermiform appendix, mimicking appendicitis ³⁴.

Colonoscopy is sometimes performed before CT or ultrasound for the evaluation of abdominal colic pain; however, such a procedure will not provide an explanation for the presented symptoms in patients who have epiploic appendagitis ³⁵.

Differential diagnosis for the imaging features of acute epiploic appendagitis include other acute inflammatory diseases, such as acute appendicitis, acute diverticulitis and sclerosing mesenteritis, fat-containing primary tumors or metastasis, and acute omental infarction, each one with characteristics imaging findings ²⁷. In particular, omental infarction is described as having many pathophysiologic similarities to epiploic appendagitis but, at CT, an omental infarction lesion is usually larger than that of epiploic appendagitis and is cake-like, centred in the omentum, and located medial to the cecum or ascending colon ³⁵.

Laboratory studies

White blood cell count, erythrocyte sedimentation rate, and C-reactive protein levels are within normal range in the majority of patients, while mild leukocytosis may occasionally be observed due to inflammatory response ²¹.

Epiploic appendagitis treatment

In the current literature, epiploic appendagitis is predominantly described as a self-limiting condition which spontaneously resolves within 2 weeks from the onset of symptoms ³⁶ and most patients are treated conservatively and nonsurgically either with or without nonsteroidal anti-inflammatory drugs ³⁵.

Epiploic appendagitis surgery

Surgery is not indicated, since the treatment is conservative with nonsteroidal anti-inflammatory drugs, according to the patient’s symptoms ²⁴. Some authors believed that surgical intervention with ligation and excision of the inflamed epiploic appendages was the only way to prevent recurrences and complications, such as adhesions and intussusception induced by inflammation ³⁷. However, invasive intervention is usually avoided due to the potential complications present in all surgical procedures. In some cases, epiploic appendagitis has been reported as an unexpected finding in patients who underwent laparotomy for acute abdominal pain with clinical suspicion of acute appendicitis or acute diverticulitis ³⁸. Epiploic appendagitis can also be a diagnosis of exclusion when other causes of acute abdominal pain are disproved.

In very rare circumstances, an epiploic appendix can protrude into a hernia sac and become an irreducible hernia ³⁹. The diagnosis of incarcerated or strangulated hernia, clinically suspected in patients with non-reducible and painful inguinal mass, should be excluded by CT imaging in the absence of radiological signs of intestinal obstruction. However, in these cases, an emergency exploration of the inguinal canal cannot be postponed in order to rule out a possible incarceration of intestinal loops. Treatment involves the excision of epiploic appendix followed by hernia repair (herniorrhaphy or hernioplasty) ⁴⁰.

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