Abstract
Epiploic appendagitis is a rare cause of acute lower abdominal pain. Epiploic appendices are fat-filled serosal outpouchings of the cecum and sigmoid colon. Primary epiploic appendagitis (PEA) is characterized by epiploic inflammation caused by torsion of the appendage leading to ischemia or thrombosis of the appendage draining vein. Secondary epiploic appendagitis occurs in association with other inflammatory conditions of the abdomen or pelvis, most commonly diverticulitis. PEA is an important clinical mimicker of more severe causes of acute abdominal pain, such as diverticulitis, appendicitis, or gynaecological causes. The ease of access to computed tomography (CT), the diagnostic test of choice, has resulted in increased recognition of PEA. The classic CT findings of PEA are an ovoid mass measuring between 1.5 and 3.5 cm surrounded by a hyperattenuating/hyperdense ring with a centrally located hyperdense area. It is important to diagnose PEA as it is self-limiting and the correct diagnosis can prevent unnecessary hospital admission, antibiotic use, or even surgical intervention. We present a case of a 65-year-old male with a history of diverticulitis, presenting with left lower quadrant abdominal pain who was diagnosed with PEA based on CT and successfully managed with conservative treatment.
Epiploic appendages are outpouchings of fat covered by visceral peritoneum on the external surface of the entire colon, measuring 1-2 centimeters (cm) in thickness and 2-5 cm in length.1 They are found in groups of 50-100, most frequently protruding off the sigmoid colon. The blood supply is via one or two small feeding arteries, and their venous drainage is by a single, central draining vein that traverses a narrow pedicle. While first described by Vesalius in 1543, the function of epiploic appendages remains unclear, but it is thought they function as a blood reservoir for the colon, provide cushioning, or protect against pathogens.2,3
Primary epiploic appendagitis (PEA), also known as appendicitis epiploica and appendagitis, is inflammation of the epiploic appendage. PEA was first described by Dockerety et al in 1956, and 73% of cases are due to torsion and inflammation, 18% due to hernia incarceration, and 8% due to intestinal obstruction.1,4,5 PEA is a rare cause of abdominal pain with clinical features similar to several conditions including diverticulitis, appendicitis, panniculitis, sclerosing mesenteritis, and gynecologic conditions (pelvic inflammatory disease, ovarian torsion, ectopic pregnancy).6,7 PEA has an incidence of 8.8 per million people per year and is 4 times higher in males, with a mean age of 44 years at diagnosis.8 PEA occurs more frequently in obese patients, patients experiencing rapid weight loss, or patients undergoing strenuous exercise.8 PEA has a high rate of recurrence in up to 40% of patients.2
Secondary epiploic appendagitis occurs due to the proximity of a normal epiploic appendage to other inflamed organs and causes intra-abdominal inflammation, most commonly due to diverticulitis and secondly due to appendicitis.6,7 In patients suspected of having acute appendicitis or diverticulitis, the incidence of PEA ranges between 2%–7%.6
Case Report
A male patient, aged 65-years, presented to the emergency room with a 3-day history of lower abdominal pain, most prominent on the left side. He had a past medical history significant for acute diverticulitis 3 months prior. He was taking no prescribed medications and had no prior surgeries. He described the pain as a constant cramping sensation, exacerbated by movement, and with periods of spontaneous worsening. The pain was associated with nausea, vomiting, and malaise. His pain was minimally relieved with acetaminophen. There was no fever, diarrhea, constipation, melena, blood per rectum, or urinary symptoms. He had one bowel movement in the past 24 hours of normal consistency. As his symptoms overlapped with those from his prior episodes of acute diverticulitis, and at the advice of his physician, he was started on a course of ciprofloxacin 500mg by mouth every 12 hours and metronidazole 500mg by mouth every 8 hours for presumed recurrent acute diverticulitis, but he did not experience any improvement after seven days.
On examination, he was afebrile with vital signs within normal ranges. He looked moderately distressed with pain. Cardiovascular and respiratory examination was normal. There was tenderness to palpation in the lower abdomen, worse in the left lower quadrant with rebound pain and guarding. The differential diagnoses included acute diverticulitis, colitis, constipation, and less likely, appendicitis, cholecystitis, and renal colic.
Laboratory investigations showed a normal complete blood count, electrolytes, creatinine, urinalysis, and C-reactive protein (CRP). A computed tomography (CT) scan of his abdomen and pelvis demonstrated, a ring-shaped area of inflammatory changes adjacent to the descending colon (Figure 1). A diagnosis of PEA was confirmed on the basis of clinical features (left lower quadrant abdominal pain and lack of fever), laboratory features (normal CRP and no leukocytosis) and a radiological finding of “ring sign.” The patient was managed conservatively with ibuprofen 400-800mg by mouth every 8 hours as needed. He experienced complete resolution of his symptoms after 7 days, with telephone follow-up.
Ring sign of epiploic appendagitis (yellow arrow) demonstrating a visceral peritoneal inflammation surrounding an epiploic appendage.
Discussion
The clinical presentation of PEA is variable, but as in this case, most typically presents with non-migrating, left lower quadrant abdominal pain with rebound tenderness of an acute onset. Fever is a finding associated with the mimickers of PEA but is usually absent in PEA. Table 1 outlines the clinical features of PEA, diverticulitis, and appendicitis. Similarly, laboratory tests (CRP, white blood cell count, lipase, transaminases, and urinalysis) and colonoscopy are normal.6
Differentiating factors between primary epiploic appendagitis, diverticulitis and appendicitis.
The diagnosis of PEA is challenging due to non-specific symptoms and signs without pathognomonic findings on investigations. Prior to the development and ease of access to advanced diagnostic imaging, the diagnosis was made surgically with only 2.5% of epiploic appendagitis cases being correctly identified pre-operatively.7,9
In 1986, Danielson et al. described the characteristic findings of epiploic appendagitis on a CT scan.10 The hallmark CT finding of PEA is an ovoid mass measuring between 1.5 cm and 3.5 cm surrounded by a hyperattenuating/hyperdense ring, representing inflammation of the visceral peritoneum surrounding the epiploic appendages, termed the ring sign.11,12 An additional sign of PEA on CT is the central dot or the dense central vessel sign that appears as a centrally located hyperdense area and corresponds to engorgement or thrombosis of the central epiploic draining vein.12 The CT findings can persist for up to 6 months before resolving.13 Secondary epiploic appendagitis is differentiated from PEA on CT by the presence of pericolic inflammatory fluid, multiple lesions, large size, and diffuse colonic wall thickening, as well as findings in keeping with other abdomino-pelvic inflammatory conditions.14,15 Ultrasonically, epiploic appendagitis appears as a noncompressible hyperechoic mass adherent to the colonic wall surrounded by a hypoechoic rim without color flow on Doppler.4 Table 1 highlights the different CT findings between PEA, diverticulitis, and appendicitis. Figure 2 demonstrates CT findings in diverticulitis that can be compared to Figure 1.
Inflamed sigmoid colon diverticulum with wall thickening and mural enhancement (yellow arrow) associated with surrounding inflammatory changes.
Despite classic CT findings, identifying epiploic appendagitis radiographically is challenging. A retrospective study by Rao and colleagues reviewed 660 CT scans to identify misdiagnosed cases of epiploic appendagitis.2 It was noted that epiploic appendagitis was present on 2% (eleven) of the CT scans, but that seven out of eleven patients were misdiagnosed with diverticulitis or appendicitis.2
Surgical management has historically been the mainstay treatment of primary epiploic appendagitis, perhaps because the diagnosis was made at laparotomy as treatment for other more serious causes of abdominal pain.2 However, given a correct pre-operative diagnosis, PEA can be managed conservatively with non-steroidal anti-inflammatories or opioid analgesia, depending on the severity of pain, and it typically resolves in 7-14 days.1,2,4,13 Antibiotics have been proposed, but the evidence for their use has yet to be determined.1,13 Definitive surgical therapy can be discussed with patients and may prevent complications of recurrence that may appear similar to a neoplastic lesion, adhesions, local abscess formation, intussusception, bowel obstruction, abscess formation, and peritonitis.4,16 On gross examination, the appendages demonstrating necrosis can appear hemorrhagic, with pathological findings of fat necrosis and inflammatory cells within the appendage.2,11
The misdiagnosis of patients with PEA has significant consequences for patients and the cost of healthcare. In the study by Rao et al.,2 all of the misdiagnosed patients were hospitalised, and six received unnecessary antibiotics, with the average medical cost rising by $4,117 USD per misdiagnosed patient. Importantly, none of the correctly diagnosed patients received antibiotics.2 In another study of 73 cases of epiploic appendagitis, 49% of patients had a surgical consultation despite mainstay therapy being conservative.17
Conclusion
In conclusion, primary epiploic appendagitis is a self-limiting inflammatory condition due to torsion and ischemia, incarceration, or obstruction of epiploic appendages.5,7,8 PEA has symptoms that mimic other causes of abdominal pain, most commonly diverticulitis and appendicitis, but patients with PEA typically lack fever, nausea, and vomiting, as well as have normal inflammatory markers without leukocytosis.1,2 The diagnosis of PEA can be made radiographically with the classic CT findings of an ovoid mass between 1.5 cm and 3.5 cm long, surrounded by a hyperattenuating ring and a centrally located hyperdense area.11,12 PEA on ultrasound appears as a noncompressible hyperechoic mass adherent to the colonic wall surrounded by a hypoechoic rim without color flow on Doppler.4 More than 90% of PEA cases can be successfully treated as an outpatient with anti-inflammatory medication, with symptoms usually abating within 2 weeks.1,4 PEA has a high rate of recurrence and laparoscopic excision may be indicated to prevent complications of intestinal obstruction, intussusception, and abscess formation.4,16 A correct diagnosis of PEA can prevent unnecessary hospitalization, antibiotic therapy, surgical consultation, and possibly surgical intervention.
- Received March 18, 2023.
- Revision received May 26, 2023.
- Accepted July 14, 2023.
References
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