A right hepatic artery forming a Moynihan’s hump with a hepatic inflammatory pseudotumor: a case description

Introduction

Hepatic hilar vessel dissection is a critical procedure in liver surgery. Hepatic artery (HA) direction anomalies are commonly overlooked risk factors that can significantly affect patient outcomes. We admitted a patient with a primary diagnosis of a liver cyst accompanied by fever. Contrast-enhanced computed tomography (CT) and magnetic resonance imaging (MRI) revealed a 10-cm cystic mass in the left hepatic lobe, which was suspected to be a biliary duct malignancy. Laparoscopic radical resection of intrahepatic cholangiocarcinoma (ICC) was performed. Intraoperatively, during the dissection of the hepatic tissue, an unusually oriented right hepatic artery (RHA) was encountered. After meticulous examination, the surgery was successfully completed. The patient had a favorable postoperative recovery. Following the histopathological examination, the patient was diagnosed with an inflammatory pseudotumor (IPT) associated with immunoglobulin G4 (IgG4) cholangitis.

Case presentation

All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the patient for the publication of this article and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

A 76-year-old male patient presented with intermittent fever and chills, and a body temperature reaching up to 39.0 ℃. He reported that he first experienced paroxysmal pain in the upper abdomen some 10 months ago. Despite anti-inflammatory treatment, his symptoms were not significantly alleviated. An ultrasound examination conducted at another hospital suggested the presence of a hepatic cyst. In pursuit of further treatment, the patient sought consultation at our hospital’s outpatient department, and was admitted with a provisional diagnosis of a liver cyst and fever.

Upon admission, the patient underwent a comprehensive set of laboratory and imaging examinations. The laboratory data revealed impaired liver function, elevated inflammatory markers, and a carbohydrate antigen 19-9 (CA19-9) level of 123 U/mL. All the other laboratory parameters fell within the normal range (Table 1). Contrast-enhanced MRI and CT of the liver revealed a cystic mass in the left lobe, with associated dilation of the left hepatic bile duct, which was more pronounced post-contrast administration, suggesting a bile duct malignancy (Figure 1). Following symptomatic treatment, which included anti-inflammatory and hepatoprotective measures, the patient’s laboratory indicators improved. The preoperative diagnosis was a hepatic cystic mass with consideration of ICC, and a differential diagnosis that included intrahepatic bile duct cystadenocarcinoma.

Figure 1 Preoperative enhanced CT and MRI images of the patient. (A) Cross-section of a MRI (T2WI) image: a cystic mass about 10.0 by 8.1 cm in size was observed between the left outer lobe and the stomach. Linear division was observed in the capsule. (B) Coronal section of a MRI image: the left intrahepatic bile duct surrounding the lesion (as indicated by the arrow) presented a bead-like dilation. (C) Coronal section of a MRI image: the arrow points to the left tortuous of the RHA. (D) Cross-section of an enhanced CT image (in the arterial phase): the early edge of the enhanced scan showed obvious enhancement. (E) Cross-section of an enhanced CT image (in the portal phase): the partially enhanced tissue adjacent to the cyst had regressed. (F) Coronal section of a CT image: the arrow points to the common bile duct present a bead-like dilation. CT, computed tomography; MRI, magnetic resonance imaging; RHA, right hepatic artery; T2WI, T2-weighted imaging.

The patient underwent laparoscopic surgery nine months ago. Upon introduction of the laparoscope, the left lateral segment of the liver was observed to be significantly atrophied, with multiple gray-white nodules on the diaphragmatic surface and a large cystic mass on the visceral surface, adhering to the lesser curvature of the stomach and the lesser omentum (Figure 2A). Based on the preoperative imaging and intraoperative findings, a decision was made to perform a radical resection for ICC, including the partial resection of the left liver and lymph node dissection. After dissecting and suspending the hepatoduodenal ligament to expose the common HA (Figure 2B), the portal vein, left hepatic artery (LHA), and RHA were skeletonized, with the LHA being suspended (Figure 2C). Further meticulous dissection in the liver revealed an aberrant RHA coursing to the left, passing behind the common hepatic duct and entering the right liver (Figure 2D). The surgical procedure successfully entailed the complete resection of the hepatic mass (Figure 3A,3B), and the clearance of lymph nodes in the gastric lesser curvature and the hepatic hilum (stations 6, 7, 8a, 8p, 12a, 12b, 12p, and 12h). The total duration of the surgery was 210 min.

Figure 2 Intraoperative 3D laparoscopic images. (A) Multiple nodules on the surface of the left half of the liver were observed. The cyst adhered to the omentum. (B) Separated adhesion between omentum and cyst on imaging. (C) During the operation, RHA and LHA were initially revealed. The LHA was suspended and protected. (D) The RHA was identified coursing behind the common hepatic duct, entering the right half of the liver. 3D, three-dimensional; CHD, common hepatic duct; LHA, left hepatic artery; PV, portal vein; RHA, right hepatic artery.

Figure 3 The gross specimen and microscopic sections of the tumor. (A) Anterior view of the tumor specimen. (B) Cross-sectional view of the tumor specimen revealing gray-green turbid bile-like fluid within a subcapsular cyst (HSB). (C) Histological image of the tumor (H&E staining, with a magnification of 40×). (D) No cancer cells were observed, but inflammatory cell infiltration was observed (H&E staining, with a magnification of 200×). H&E, hematoxylin and eosin; HSB, hepatic subcapsular biloma.

Pathological findings showed IPT (Figure 3C,3D) and reactive hyperplasia of lymph nodes. The immunohistochemistry results were as follows: CK7 (biliary epithelial cell +), CK20 (–), CD35 (–), ALK (–), SMA (myoepithelial cell +), S-100 (–), CD117 (–), CD68 (+), Ki-67 (15%+), and IgG4(+). Postoperatively, the patient experienced a transient episode of fever but did not develop any other complications. The patient was later discharged in a stable condition.

Discussion

IgG4 cholangitis-associated IPT with intrahepatic biloma

IPT is a lesion characterized by the proliferation of myofibroblasts, accompanied by the infiltration of inflammatory cells. Due to atypical imaging features and clinical manifestations, it is frequently misdiagnosed as a hepatic malignant tumor (1). It most commonly occurs in the lungs and orbit, and is rarely seen in the liver. The etiology of hepatic IPT is still unclear, but it may be closely related to factors such as hepatitis virus infection, trauma, IgG4 cholangitis, and primary sclerosing cholangitis. The most common symptoms are abdominal pain, fever, and weight loss (2).

In terms of its imaging and clinical presentation, IPT is often indistinguishable from ICC and other space-occupying lesions in the liver. Most reports related to hepatic IPT are associated with IgG4-related sclerosing cholangitis, manifesting as solid lesions, with a minority showing intralesional liquefactive necrosis (3). To date, only one case of IgG4-related thymic cysts associated with IPT has been reported (4), and there has been no report of hepatic IPT combined with cystic changes.

Intraoperative cystic fluid aspiration revealed gray-green, turbid fluid, indicating communication between the cyst wall and the biliary tract, concurrent with biliary tract infection. Integrating preoperative imaging, intraoperative manifestations, histopathological examination, and immunohistochemical profiling, the definitive diagnosis for this patient was IgG4-related sclerosing cholangitis, hepatic IPT, and hepatic subcapsular biloma (HSB).

HSB is characterized by encapsulated bile accumulation in the liver parenchyma or under the liver capsule, resulting from bile leakage from intrahepatic bile ducts due to various etiologies. Radiologically, HSB lesions present as cystic tumor-like structures, with previous reports predominantly linking them to iatrogenic injury following biliary tract surgery (5). This patient likely developed HSB secondary to inflammatory bile duct lesions, leading to localized bile duct wall weakness or rupture, with subsequent bile leakage and accumulation under the capsule.

The patient’s radiological presentation, featuring a cystic mass in the left hepatic lobe with beaded dilation and bile duct enhancement (Figure 1), coupled with the persistent elevation of the tumor marker CA19-9, led us to strongly suspect ICC. Consequently, the preferred surgical approach was radical resection. Regrettably, the patient’s IgG4 levels were not assessed preoperatively. Ten days after the operation, the patient’s serum IgG4 level was found to be 2.68 g/L, which was slightly above the normal range. Notably, Yamamura et al. (6) reported a case of IgG4-related sclerosing cholangitis co-occurring with cholangiocarcinoma. Although a causal relationship between the two conditions has not yet been established, cholangitis may be considered a premalignant condition. Thus, despite the benign final diagnosis, we maintain that surgical intervention was the optimal choice in this case.

The rare RHA running variation

HA variations are significant contributors to adverse events in hepatobiliary and pancreatic surgery. The RHA exhibits the highest incidence of anatomical variation, manifesting in multiple distinct patterns. These variations mainly include: origin anomalies such as direct emergence from the abdominal aorta or superior mesenteric artery, accessory vessel variants such as the presence of an accessory RHA, circumnavigating the anterior aspect of the common hepatic duct, and abnormally tortuous bulge deformity. This patient exhibited tortuosity of the RHA. Such deformities refer to the abnormal elongation, thickening, and tortuosity of the RHA, also known as the “caterpillar hump” or Moynihan’s hump, and are considered the “most dangerous” RHA variation (7).

Previous literature reports the incidence of tortuosity of the RHA to be approximately 1.3–13.3%, with an average level of 6.9% (8). This type of variation often presents a characteristic “caterpillar-like” encirclement. The etiology of the tortuosity deformity remains unclear, but it may be associated with liver cirrhosis, hepatic morphological abnormalities, and the persistence of an accessory RHA during embryonic development (9). Theoretically, the convexity of this encirclement can be directed downwards, upwards, to the right, or to the left, with the tortuous artery passing either dorsally or ventrally to the common hepatic duct (10). Since these variations are mostly discovered during laparoscopic cholecystectomy (7), the Moynihan’s hump reported in the previous study was caused by the RHA’s rightward tortuous bulging, resulting in an extremely short cystic artery (CA) (8). Conversely, in the patient in the present case, the RHA exhibited a leftward tortuous course (Figures 1C,4), passing behind the LHA and the common hepatic duct, and then looping to the right to enter the right liver. The CA originated from the LHA (Figure 4B). As a CA originating from the LHA is usually a congenital variation, and the duration of cholangitis was unknown, we had no basis to consider the correlation between tortuous RHA and cholangitis disease. A systematic search of the PubMed and Geen Medical database literature revealed no reports of this type of variation to date.

Figure 4 The course of arteries under the angiography mode. (A) The arrow indicates the leftward movement of RHA Moynihan’s hump; (B) [1] CA; [2] S4 branch of the LHA; [3] RHA forming a Moynihan’s hump. CA, cystic artery; LHA, left hepatic artery; RHA, right hepatic artery; S4, segment 4.

Damage to the RHA can cause complications such as liver ischemia, atrophy, necrosis, liver failure, and even death. An insufficient understanding of RHA variations and its improper handling during surgery are significant causes of postoperative complications. Preoperative imaging studies, such as CT angiography or magnetic resonance angiography, provide essential insights into these variations. The careful identification of anatomical structures during surgery, meticulous dissection, and proper protection of the HA are crucial to prevent accidental ligation or injury, ensuring the safety of the surgical procedure.

Conclusions

The novelty of this case is underscored by the unique trajectory of the RHA, which has not been previously reported, and the co-occurrence of hepatic IPT with biloma. Surgical intervention was deemed the best course of action in this case. Surgeons should exercise heightened vigilance in relation to Moynihan’s hump due to its potential implications for surgical planning and patient outcomes.

Acknowledgments

None.

Footnote

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://qims.amegroups.com/article/view/10.21037/qims-2025-385/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the patient for the publication of this article and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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