Epiploic appendagitis is ischemic necrosis of small fat tissue protrusions (epiploic appendages) along the colon due to torsion or spontaneous venous thrombosis. It is a self-limiting condition that usually does not require surgery. It is one of the most common benign causes of left lower quadrant pain. Characterized on CT by a fat-density oval lesion surrounded by a hyperattenuating ring (hyperattenuating ring sign) and perifocal inflammation. Frequently confused with acute appendicitis and diverticulitis.
Age Range
25-65
Peak Age
45
Gender
Equal
Prevalence
Uncommon
Epiploic appendages are 1-5 cm fat tissue protrusions on the colonic serosa, each supplied by a single artery and vein. Torsion or spontaneous venous thrombosis of the vascular pedicle leads to venous congestion and subsequent ischemic necrosis. Necrotic fat causes perifocal inflammatory response. On imaging, necrotic fat appears as oval lesion between -40 and -80 HU on CT. The surrounding hyperattenuating ring reflects a thin reactive layer formed by inflammatory exudate and fibrin deposition around the fat tissue. Central hyperdense focus corresponds to the thrombosed venous pedicle. Inflammation extends to surrounding fat and adjacent peritoneal surfaces creating perifocal stranding.
Thin hyperattenuating ring surrounding fat-density oval lesion adjacent to colon. Reflects reactive layer of inflammatory exudate and fibrin deposition around necrotic fat. Pathognomonic finding for epiploic appendagitis that confirms diagnosis on CT and prevents unnecessary surgical intervention.
Thin hyperattenuating ring surrounding a 1-5 cm fat-density (-40 to -80 HU) oval lesion adjacent to colon. Ring is 1-3 mm thick, smooth and continuous, reflecting inflammatory exudate and fibrin deposition. Visible even on non-contrast CT. This finding is pathognomonic for epiploic appendagitis.
Report Sentence
Hyperattenuating ring surrounding a fat-density oval lesion adjacent to sigmoid colon, consistent with epiploic appendagitis.
Small round hyperdense focus in center of fat-density lesion (central dot sign). Represents thrombosed vascular pedicle. Not seen in every case but strengthens diagnosis when present. Usually appears as punctate hyperdensity of 1-3 mm.
Report Sentence
Central hyperdense focus (central dot sign) within fat-density lesion, consistent with thrombosed vascular pedicle.
Increased density in mesenteric fat surrounding the lesion (fat stranding). Reflects perifocal inflammatory response. Extent of stranding is proportional to severity of inflammation. Limited stranding favors epiploic appendagitis while extensive stranding suggests diverticulitis or appendicitis.
Report Sentence
Increased density in mesenteric fat surrounding the lesion (fat stranding), consistent with perifocal inflammatory response.
Adjacent colonic wall maintains normal thickness (<3 mm) and enhancement pattern. Absence of colonic wall thickening is an important distinguishing feature from diverticulitis. Lesion is adjacent to colonic serosa but does not involve the colonic wall.
Report Sentence
Colonic wall adjacent to the lesion maintains normal thickness with no wall involvement, supporting exclusion of diverticulitis.
Oval, hyperechoic, non-compressible mass adjacent to colon on US. Surrounding hypoechoic halo (inflammatory ring) may be seen. Avascular or minimal peripheral vascularity on Doppler. US sensitivity is lower than CT but may be useful in evaluating left lower quadrant in thin patients.
Report Sentence
Oval hyperechoic non-compressible mass adjacent to colon with surrounding hypoechoic halo on US, consistent with epiploic appendagitis.
Oval lesion with fat signal (hyperintense) on T1 adjacent to colon on MRI. Shows signal loss on fat-suppressed sequences confirming fat content. Surrounding T1 hypointense inflammatory ring is seen. MRI can be used as alternative to CT for diagnosis especially in pregnant and young patients.
Report Sentence
Oval fat-signal lesion on T1 adjacent to colon with surrounding inflammatory ring on MRI, consistent with epiploic appendagitis.
Criteria
Ischemic necrosis from spontaneous torsion or venous thrombosis. No underlying colonic pathology. Self-limiting, conservative treatment sufficient. Symptoms resolve in 1-2 weeks.
Distinct Features
Normal colonic wall, isolated fat lesion, resolution with conservative treatment
Criteria
Epiploic appendage inflammation secondary to adjacent organ inflammation such as diverticulitis, appendicitis, or cholecystitis. Treated together with primary pathology.
Distinct Features
Accompanying colonic wall thickening or diverticulum, multiple inflammatory foci
Criteria
Sequela of prior acute episode. Necrotic fat may calcify over time forming 'peritoneal mice' (loose bodies). Asymptomatic, incidental finding. Appears as small free structures containing fat and calcification on CT.
Distinct Features
Calcified nodule, free peritoneal body, asymptomatic, incidental finding
Distinguishing Feature
Intra-abdominal abscess shows rim enhancement, central fluid, and gas bubbles; epiploic appendagitis shows fat-density oval lesion with hyperattenuating ring; fever and leukocytosis are prominent in abscess
Distinguishing Feature
Mesenteric ischemia shows bowel wall thickening, mesenteric vessel occlusion, and pneumatosis; epiploic appendagitis has normal bowel wall and no vascular pathology
Distinguishing Feature
Desmoid tumor is solid soft tissue mass with homogeneous enhancement; epiploic appendagitis shows fat-density oval lesion with hyperattenuating ring; desmoid presents chronically while epiploic appendagitis presents acutely
Distinguishing Feature
Peritoneal endometriosis shows T1 hyperintense hemorrhagic foci with cyclic pelvic pain; epiploic appendagitis shows T1 fat signal and presents with localized acute pain adjacent to colon
Urgency
routineManagement
conservativeBiopsy
Not NeededFollow-up
no-follow-upEpiploic appendagitis is a self-limiting condition and conservative treatment (NSAIDs, rest) is sufficient. Surgery is not required. Correct CT diagnosis prevents unnecessary appendectomy or diverticulitis treatment. Symptoms typically resolve within 1-2 weeks. Rare complications: adhesions, bowel obstruction, abscess formation. The most important step in treatment is correct diagnosis.
Epiploic appendagitis is self-limiting. Diagnosis prevents unnecessary surgery (misdiagnosis as appendicitis/diverticulitis). Symptomatic treatment with NSAIDs is sufficient. Resolves spontaneously in 1-2 weeks.