Infarction of a fatty appendage of the falciform ligament - A case report

Clinical History

A 45-year-old man presented with a 1 day history of right upper quadrant pain with guarding. Laboratory tests revealed an elevated white cell count but other tests, including liver enzymes and amylase, were normal. Ultrasound examination was non-contributory and a CT of the abdomen and pelvis was acquired.

Imaging Findings

CT (64-slice helical CT [Toshiba Aquilion 64, Toshiba, Japan], 3 mm reconstructions, with 100 ml intravenous contrast [Iomeron 350, Iomeprol, Bracco, UK]) demonstrated an ovoid fat density structure arising from inferior to the falciform ligament and lying anterior to the left lobe of the liver. There was streaky increased attenuation noted around the base of the lesion, with a “twisting” morphology discernable on the sagittal reformatted images. An enhancing margin was noted around the lesion. There was no associated focal liver or gallbladder lesion and no free intraperitoneal gas or fluid. The abnormality was distinct from the adjacent transverse colon.

The findings were compatible with infarction of a fatty appendage of the falciform ligament, of which to our knowledge there has only been 1 case reported worldwide to date [2].

Discussion

Intraperitoneal focal fat infarction (IFFI) is a term encompassing a range of conditions where the common underlying pathology is infarction of fatty tissue. Certain forms of IFFI are well described such as epiploic appendigitis (EA) and omental infarction (OI) [1]. Infarction of a fatty appendage of the falciform ligament has only been reported once in the literature [2] and represents an exceedingly rare location for IFFI. IFFI may mimic common pathological processes and is frequently misdiagnosed [3]. It is important to identify the imaging findings in IFFI as the recognised treatment is conservative [4]. Correct diagnosis obviates further, potentially harmful, investigation and treatment including surgery [5].

The imaging findings in IFFI have been extensively reviewed [1, 3]. A summary is present below.

Ultrasonographic findings in EA are typically of a hyperechoic, non-compressible intraabdominal mass at the site of tenderness fixed to the organ of origin. A central hypoechoic area thought to correspond to haemorrhagic change may be present. Colour Doppler is typically absent which may help distinguish IFFI from other inflammatory conditions such as diverticulitis [6]. Findings in OI are analogous but the mass tends to be larger and a hypoechoic centre is more often present.

CT of EA demonstrates an area of fat density with hyper-attenuating streaks centred at the site of infarction arising from the colon. A 2-3mm peripheral rim of hyper-attenuation is often seen corresponding to inflammation of the visceral peritoneum. A central area of higher attenuation may be present, corresponding to the central hypoechoic area seen on US (the “central dot sign”). This central area may calcify over time and even detach to form a peritoneal loose body [7]. Adjacent thickening of the bowel wall is sometimes seen but is not considered discriminatory. In OI a larger, cakelike, fatty mass is seen anterior and medial to the ascending colon. Peri-lesional hyperattenuation is absent.

MRI has infrequently been performed in the setting of IFFI. In EA the appendage is hyperintense on T1WI with loss of signal on fat-suppressed T2-weighted images. Peripheral inflammatory changes appear hypointense on T1WI, hyperintense on T2WI and enhance on T1 weighted fat-suppressed sequences [7].

The authors of the only other reported case of IFFI involving a fatty appendage of the falciform ligament suggest CT is key to a definitive diagnosis and highlight the importance of multiplanar reconstruction of images [2]. CT excludes adverse features such as pneumoperitoneum and aids diagnosis of more common or serious conditions.

Differential Diagnosis List

Final Diagnosis

Infarction of fatty appendage of the falciform ligament (IFFI).

URL:	https://www.eurorad.org/case/10799
DOI:	10.1594/EURORAD/CASE.10799
ISSN:	1563-4086