Abscess of the Falciform Ligament Mimicking an Extrahepatic Bile Duct Tumour: a Case Report and Review of the Literature

The abscess of the falciform ligament (FL) is a rare condition in adult patients and can occur in the context of acute cholangitis, acute pancreatitis, torsion of the FL itself or spontaneously. Abdominal imaging often helps making a correct diagnosis. We reported a case of FL abscess and the review of the literature. A 78-year-old male was admitted to hospital with acute pancreatitis secondary to hypercholesterolaemia; the computed tomography (CT) scan of the abdomen demonstrated the presence of appendagitis of the FL. After receiving medical treatment, the patient was discharged with planned clinical and radiological follow-up. The magnetic resonance cholangio-pancreatography (MRCP) and abdominal CT scan showed the progression of the inflammatory changes to the porta hepatis, which raised the suspicion of an extrahepatic bile duct tumour; given the diagnostic uncertainty, the patient underwent diagnostic laparoscopy that allowed for the correct diagnosis and treatment. The abscess of the FL is uncommon in adults and radiological findings can be misinterpreted as other clinical conditions; a high index of suspicion is required to formulate a correct diagnosis with the aid of diagnostic laparoscopy.


Introduction
The falciform ligament (FL) is a peritoneal fold that attaches the anterior surface of the liver to that of the inferior diaphragm and anterior abdominal wall [1]. The abscess of the FL is uncommon in adults as it occurs more frequently in neonates, thus representing a potential diagnostic challenge [2][3][4][5]. We report a case of FL abscess together with a review of the recent literature.

Ethics
The patient gave full consent for the publication of the case report and no identifiers have been used.

Case Presentation
A 78-year-old male presented to the hospital with a 4-day history of post-prandial vomiting, upper abdominal pain and bloating, on 23/01/2019. On examination, there were no signs of systemic compromise and the abdomen was soft, distended and tender on deep palpation of the epigastrium. Patient's comorbidities were medically controlled essential hypertension, hypercholesterolaemia and gout, and he underwent coronary stent insertion for ischaemic heart disease, 18 years before. There was no history of alcohol and tobacco use. As shown in Table 1, serum blood tests demonstrated leucocytosis with neutrophilia, hyperamylasaemia, and derangement of liver and renal functions, respectively.
An abdominal ultrasound (USS) was prompted and no abnormalities were demonstrated; given the clinical and biochemical presentation, a computed tomography (CT) of the abdomen and pelvis was arranged, to evaluate the periampullary area; the scan showed mild inflammatory changes of the FL only (Fig. 1). A diagnosis of mild acute pancreatitis, in accordance with the modified Atlanta 2013 [6] and FL appendagitis, was formulated; the patient was treated with naso-gastric tube insertion, intravenous Ringer's lactate infusion, opioid analgesia and aminoglycoside antibiotics.

This article is part of the Topical Collection on Surgery
Following clinical and biochemical improvement, he was discharged 8 days after admission with planned clinical and radiological follow-up. The magnetic resonance cholangiopancreatography (MRCP) demonstrated a deformed FL, surrounded by local inflammatory changes, diffuse narrowing of the common hepatic and intrahepatic ducts, and abnormal soft tissue signal at the porta hepatis on T2 sequences, respectively ( Fig. 2). At the time, the patient complained of poor appetite, weight loss and epigastric discomfort, while the serum liver function tests were within normal range.
After discussion at multidisciplinary level, a thoracoabdominal CT scan was arranged in 2 weeks' time; that showed progression of the abnormal soft tissue density at the porta hepatis; therefore, a diagnostic laparoscopy was planned on 14/05/2019. Upon surgery, the FL looked bulky, while the liver was unremarkable. Total excision of the FL was performed with the harmonic scalpel (Fig. 3). The early postoperative course was uneventful and the patient was discharged home, on day 2; the histo-pathological analysis of the specimen showed abscess in the context of fat necrosis with no evidence of malignancy.
Clinical and radiological follow-up was prompted at 6 months; the patient did not report abdominal symptoms and the abdominal CT scan demonstrated a marked reduction of the soft tissue inflammation at the porta hepatis. A further abdominal USS was performed 16 months after surgery and no abnormalities were demonstrated.

Discussion
In adults, infections of FL including abscesses are rare and tend to occur in the context of biliary pathologies like acute cholangitis or acute pancreatitis [7][8][9][10]. The close anatomical relationship of the proximal portion of the FL with the liver might explain how inflammatory and infectious conditions occurring at the porta hepatis spread to the FL. Other possible pathophysiological mechanisms of the onset of FL abscess could be the formation of an infected haematoma or tissue necrosis, secondary to the damage of the vascular supply to the FL, i.e. in the circumstances of inflammatory processes of the peritoneum or torsion of the FL itself [11][12][13]. Moreover, this condition can occur without an evident cause, as FL abscess of unknown aetiology had been reported in the literature [14,15].
In the present case report, the patient developed an abscess of the FL in the context of acute pancreatitis secondary to hypercholesterolaemia. The initial radiological imaging showed mild inflammatory changes to the FL while the pancreas looked unremarkable; this aspect is well reported in that mild pancreatitis can be associated with normal CT findings [6]. The inflammatory process progressed further and involved the tissues surrounding the porta hepatis; that was associated with the narrowing of the intra-and extrahepatic ducts and we suggest it explained the transient increase of bilirubin. It can be argued that, in this particular case, the pathophysiological mechanism underpinning the initial inflammation of the FL could be similar to that of mesenteric panniculitis, which had been described in association with acute pancreatitis [16,17]. Unfortunately, the lack of microbiological culture of the surgical specimen precluded a better understanding of the potential aetiology of the disease.
In the published literature, the abdominal USS and CT had been reported as the most common investigations to assess the FL [4,5], although the CT seems to be more Amylase 2615 28-100 U/L Fig. 1 Abdominal computed tomography performed on first patient's hospital admission sensitive than USS [11]. The role of MRCP in this context had not been evaluated. In our case, diagnosis was only possible upon surgery. Given its rarity, the abscess of the FL is often mistaken for other diseases (e.g. hepatic abscess), and its diagnosis and treatment are often delayed; therefore, a strong clinical suspicion is required to identify and treat this condition promptly [9]. Therapeutic options of FL abscess include percutaneous drainage under radiological guidance, surgical drainage and surgical excision of the FL [8,9,14]; drainage only seems to be associated with a higher failure rate; therefore, surgical excision of the ligament is advocated [8,15]. In our case, the laparoscopic excision allowed for a definitive treatment.
Given the small amount of available published data, robust conclusions on the subject cannot be drawn; there is some evidence that laparoscopic excision of the FL yields better outcomes when compared to radiological or surgical

Conclusions
This case reports on the diagnostic challenge of an uncommon clinical condition. The initial CT scan demonstrated appendagitis of the FL but further imaging failed to evaluate disease progression towards abscess formation and findings were even misinterpreted as concerning for an extrahepatic bile duct tumour. Moreover, while patient's abdominal symptoms persisted, serum biochemistry was within normal range, thus contributing to the suspicion of neoplastic disease. Eventually, diagnostic laparoscopy allowed for a correct diagnosis and treatment of patient's condition.
In conclusion, FL abscess is uncommon in adults; when the inflammation spreads to its liver insertion, findings can be misinterpreted on radiological imaging. In such circumstances, diagnostic laparoscopy may help achieving the correct diagnosis and allowing for definitive treatment at the same time.
Author Contribution All authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Aris Alexiadis. The first draft of the manuscript was written by Aris Alexiadis and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.
Conceptualization Code Application Not applicable as no software was used.

Declarations
Ethics The patient gave full consent for the publication of this case report.
Ethical Approval Ethical approval was not obtained, as the study consisted of a case report.

Consent to Participate and for Publication
Participant's consent to the study and its publication was obtained.

Conflict of Interest
The authors declare no competing interests.