Torsion of the Falciform Ligament Fatty Appendage: An Overlooked Cause of Abdominal Pain in Adults

Introduction

The falciform ligament is often clinically overlooked as a vestigial remnant of the ventral embryonic mesentery that anatomically separates the liver into its asymmetric right and left hepatic lobes [1].

The fatty appendage of the falciform ligament is an extraperitoneal focus of fat, of varying size, commonly found within or attached to the falciform ligament. Though torsion of the fatty appendage of the falciform ligament is rare, it can commonly mimic other more common causes of acute upper-abdominal pain [2,3], including hepatobiliary and gastrointestinal causes such as cholecystitis, epiploic appendagitis, and pancreatitis. Torsion of the fatty appendage of the falciform ligament causes twisting and thrombosis of its central vein, leading to fat necrosis and infarction [4].

In this article, we present 2 cases of torsion of the fatty appendage of the falciform ligament. By discussing the clinical presentation, imaging findings and potential treatment options, we aim to raise awareness of this pathology as a potential differential diagnosis for acute abdominal pain.

Case Reports

CASE 1:

A 47-year-old Chinese woman presented to the emergency department with a one-day history of right upper-quadrant abdominal pain. This was associated with non-bilious vomiting and reduced appetite. She reported no recent travel history or change in bowel habit.

On examination, her vital signs were within normal limits and she was afebrile. Tenderness was elicited in the right upper-abdominal quadrant, and Murphy’s sign was positive. Her laboratory results showed slightly raised C-reactive protein, while other tests (full blood count, liver function tests, and serum lipase) were unremarkable. Chest and abdominal radiographs revealed no significant pathology.

She was treated with analgesics, with minimal improvement in symptoms. A computed tomography (CT) scan of the abdomen and pelvis with contrast was performed, which showed oval shaped elongated fat-density structure, extending from the diaphragmatic dome, between the right and left hepatic lobes, to the umbilicus. Associated focal fat stranding and minimal free fluid was also present. These findings likely represented torsion of the fatty appendage of the falciform ligament (Figures 1, 2). The gallbladder showed mild mural thickening without significant pericholecystic fat stranding. No radio-dense gallstone or biliary tree dilatation was detected.

She was managed conservatively with analgesia, anti-emetics and antibiotics. She had an uneventful inpatient stay and was discharged in good health 2 days later.

CASE 2:

A 32-year-old Chinese man presented to the emergency department with persistent generalized abdominal pain for several days, most marked at the epigastrium. He had previously tried taking antacids, with little improvement in symptoms. He denied having nausea, vomiting, or diarrhea. He reported occasional consumption of alcohol (no more than 1 standard drink on most days).

His vital signs were normal and he was afebrile. On examination, there was tenderness elicited at the epigastrium without overt signs of peritonism. Laboratory tests showed normal serum lipase and leukocyte count.

A CT abdomen and pelvis scan with contrast was performed, which demonstrated increased density and surrounding inflammatory changes along the course of the falciform ligament, extending from the diaphragmatic dome to the anterior abdominal wall. This was suspicious for torsion of the fatty appendage of the falciform ligament (Figures 3, 4). The pancreas was normal in appearance.

He was managed conservatively with analgesia and intravenous antibiotics. His symptoms gradually resolved over the next 2 days and he was discharged in good health.

Discussion

ANATOMY AND PATHOLOGIES OF THE FALCIFORM LIGAMENT:

The falciform ligament is a sickle shaped, double-layered extension of the parietal peritoneum connecting the liver to the ventral abdominal wall and under-surface of the diaphragm [1]. The falciform ligament contains the ligamentum teres, paraumbilical veins, and a variable amount of extraperitoneal fat [5]. The arterial blood supply to the falciform ligament is usually derived from the left inferior phrenic or middle hepatic arteries. The venous drainage is into the left inferior phrenic vein [1].

Primary pathologies of the falciform ligament are rare and include cysts, lipomas, tumors, abnormal vascularization secondary to portal hypertension, internal hernias, gangrene due to necrotizing pancreatitis, and torsion of the fatty appendage of the falciform ligament [2,6].

CLINICAL PRESENTATION AND IMAGING FINDINGS:

Intra-abdominal fat infarction (IFFI) refers to focal lipomatous tissue necrosis in various abdominal locations, more commonly in the greater omentum and epiploic appendages, although there are rare instances of fatty appendage of the falciform ligament involvement reported, such as in the 2 above cases [6]. A recent literature review by Divakar et al identified only 18 case reports of IFFI involving the falciform ligament [3]. These cases predominantly occurred in adults, but pediatric presentations have also been documented [6].

Patients usually present with acute right upper-abdominal or epigastric pain and nausea [3]. Anorexia and vomiting were other less commonly reported symptoms [3]. Laboratory markers are often unrevealing apart from possible non-specific elevation of the inflammatory markers and leukocytosis [3].

The first-line imaging in patients with abdominal pain tend to be abdominal radiographs and ultrasound studies of the abdomen. Radiographs are often of limited utility due to non-visualization of the falciform ligament and limited assessment of any associated secondary signs of IFFI. Ultrasound studies typically demonstrate a hyperechoic, non-compressible mass with surrounding inflammatory change, deep to the rectus abdominis and with probe tenderness. Internal color Doppler flow is typically absent. The limitations of ultrasound examinations are that they are heavily operator-dependent and there may be limited access to scans outside regular working hours. Hamal et al also reported that less than half of case reports showed 1 or more of the above sonographic features [3], potentially raising the concern for a missed diagnosis.

A CT abdomen and pelvis with contrast is considered the gold standard for diagnosis due to its ready availability in most emergency departments, quick scan acquisition, and good sensitivity. Multiplanar views depict inflammatory changes of the falciform ligament with a peripheral rim of hyper-attenuation (the hyperattenuating rim sign) [3]. The central dot sign, representing a thrombosed central vein, is regarded as pathognomonic of certain IFFI like epiploic appendagitis, although this finding is not seen in all cases. CT would also be useful in evaluating for any complications like abscess formation and excluding other causes of abdominal pain. In both of our cases, gallbladder mural edema was observed, likely secondary to reactive changes from adjacent inflammation. Crucially, there was no significant pericholecystic fat stranding to suggest acute cholecystitis.

DIFFERENTIAL DIAGNOSIS AND MANAGEMENT:

Possible radiological differential diagnoses to consider are liposarcoma or metastases of the falciform ligament, but these would likely not show associated inflammatory changes, and also present in a different clinical context.

Treatment of IFFI of the falciform ligament remains a subject of debate, with several early cases confirmed on histopathology after surgical excision [7]. There has, however, been a shift towards conservative management, usually with analgesia, anti-emetics, and possibly antibiotics in conjunction with local anti-microbial guidelines [3]. Surgical interventions may still be required in instances of clinical deterioration or complications such as abscess formation necessitating image-guided drainage [8]. Nonetheless, the condition is usually self-limiting and resolves spontaneously, with most patients improving under conservative management without the need for surgical intervention [4]. Recognition of the characteristic CT features can help clinicians make a confident diagnosis and avoid unnecessary surgical intervention.

Conclusions

IFFI of the falciform ligament is a rare but important cause of right upper-abdominal or epigastric pain that can mimic other acute abdominal pathologies. The 2 patients who presented to our institution had non-discriminatory clinical examination findings but quite classical imaging appearances. It is important for clinicians and radiologists to be aware of this condition to enable prompt and accurate diagnosis, appropriate management, and to avoid unnecessary surgery.