Abstract
Intrahepatic cholangiocarcinoma (iCCA) is an aggressive biliary malignancy in which complete surgical resection remains the only potentially curative treatment. Caudate lobe tumours are particularly challenging because of their proximity to major vascular structures, including the inferior vena cava (IVC). Although iCCA commonly spreads through vascular, lymphatic, perineural, and biliary pathways, extension along retrohepatic ligamentous planes has not previously been described. We present a 56-year-old man with caudate-origin iCCA and bulky nodal disease causing biliary obstruction. Following neoadjuvant gemcitabine, cisplatin, and pembrolizumab, the patient underwent an open right hepatectomy with caudate resection and lymphadenectomy. Intraoperatively, the tumour demonstrated retrocaval extension along the hepatocaval ligament posterior to the IVC, representing a previously unreported dissemination pathway. En bloc resection achieved negative margins. This case expands the current understanding of iCCA tumour behaviour and highlights the importance of recognizing retrohepatic ligamentous extension during surgical resection.
Introduction
Intrahepatic cholangiocarcinoma (iCCA) is an aggressive primary liver malignancy associated with high rates of local invasion and poor long-term survival, with surgical resection representing the only potentially curative treatment [1, 2]. Tumour spread commonly occurs through vascular, lymphatic, perineural, and biliary invasion, as well as infiltration through stromal and connective tissue planes [3, 4]. The mass-forming subtype, the most common presentation of iCCA, typically demonstrates radial expansion into adjacent hepatic parenchyma rather than extension along the biliary tree [5, 6]. This infiltrative behavior is particularly relevant in caudate-origin tumours because of their close relationship with the inferior vena cava (IVC), hepatocaval ligament, and hepatic venous confluence. Imaging studies further support this behavior, describing irregular margins and progressive enhancement patterns consistent with parenchymal invasion rather than ductal extension [6–8].
Despite the invasive nature of iCCA, the specific anatomical pathways of spread in caudate-origin tumours remain incompletely characterized. Although extension into adjacent hepatic segments and vascular structures has been described, propagation along retrohepatic connective tissue planes, particularly the hepatocaval ligament, has not been previously reported [2, 9]. Given the propensity of iCCA for stromal and connective tissue infiltration [3, 4], extension along retrohepatic ligamentous planes may represent an underrecognized dissemination pathway.
This report describes a unique case of caudate-origin iCCA with retrocaval extension along the hepatocaval ligament, identified intraoperatively during an open right hepatectomy with en bloc caudate resection (Video 1).
Case presentation
We present a 56-year-old male with a history of prostate cancer, type 2 diabetes mellitus, hypertension, hyperlipidemia, and obstructive sleep apnea, who initially presented with obstructive jaundice. Cross-sectional imaging demonstrated a poorly defined hepatic lesion centered in the caudate lobe with extension into the right posterior hepatic sector and bulky nodal disease causing biliary obstruction. Endoscopic retrograde cholangiopancreatography with biopsy confirmed microsatellite-stable intrahepatic cholangiocarcinoma. Biliary stenting was performed for decompression.
Given nodal disease and borderline resectability, the patient underwent neoadjuvant systemic therapy with gemcitabine, cisplatin, and pembrolizumab, followed by gemcitabine and pembrolizumab, achieving a favorable radiographic response (Fig. 1). He subsequently underwent an open right hepatectomy with en bloc caudate resection.
Pre- and post-neoadjuvant therapy computed tomography (CT) scans (A) pre-neoadjuvant CT scan showing a lesion centered in the caudate lobe, in close proximity to the retrohepatic inferior vena cava (IVC), without clear evidence of retrohepatic or ligamentous involvement. (B) Post-neoadjuvant CT scan demonstrating decreased tumor size after therapy.
Following parenchymal transection along the standard right hepatectomy plane, to the right of the middle hepatic vein, a previously unappreciated retrocaval tumour extension posterior to the IVC became evident intraoperatively (Video 1). The tumour extended along the hepatocaval ligament toward the right liver. Importantly, the paracaval caudate parenchyma was not directly involved, suggesting propagation through a posterior ligamentous plane rather than direct trans-parenchymal extension (Fig. 2).
Resected specimen demonstrating tumor extension along the Hepatocaval ligaments (A) anterior view. Arrow indicating the hepatocaval ligament. (B) Posterior view. Arrow indicating the hepatocaval ligament.
Upon recognition of this finding, division of the retrohepatic attachments was deferred to avoid tumour violation. Circumferential dissection around the IVC was then performed to safely mobilize the retrohepatic component while preserving the oncologic plane.
Final pathology revealed a 7.3 cm poorly differentiated small duct type iCCA extending along the hepatocaval ligament, staged as ypT2N1, with lymphovascular invasion and negative surgical margins (R0). Three of 15 lymph nodes were positive for metastatic disease (Fig. 3).
Final pathology. (A) Gross pathology. The involved hepatocaval ligament is inked in red. (B) Microscopic pathology.
The postoperative course was notable for acute kidney injury on chronic kidney disease, managed medically. The patient was discharged in stable condition. At 2-month follow-up, he remained asymptomatic without radiographic evidence of recurrence (Fig. 4).
Postoperative CT scan with no evidence of recurrence and adequate hypertrophy of the remaining liver.
Discussion
This case demonstrates a previously undescribed pattern of tumour dissemination in intrahepatic cholangiocarcinoma, consisting of retrocaval extension along the hepatocaval ligament behind the IVC. This pathway was not identified on preoperative imaging and only became evident intraoperatively after parenchymal transection, directly influencing surgical strategy. Recognition of this finding prompted modification of the operative approach, allowing preservation of the oncologic plane and achievement of an R0 resection.
The aggressive and infiltrative biology of iCCA is well established, with recognized mechanisms of spread including vascular, lymphatic, perineural, and stromal invasion [2–4]. Histopathologic studies have shown that tumour cells may infiltrate connective tissue planes and portal tracts, favoring dissemination through low-resistance anatomical pathways [3, 4]. However, macroscopic and radiologic descriptions of iCCA generally emphasize radial parenchymal invasion rather than organized propagation along discrete ligamentous structures [5, 6].
Tumours involving the caudate lobe are particularly challenging because of their close relationship with the IVC and major hepatic vascular structures. Previous reports describing posterior extension of caudate tumours have largely attributed this behavior to direct parenchymal or vascular invasion [10, 11]. To our knowledge, continuous retrocaval propagation along the hepatocaval ligament has not been previously reported [6, 12].
Several intraoperative and pathological findings support the hepatocaval ligament as the primary route of dissemination in this case. First, the tumour extended as a cohesive retrocaval sheet posterior to the IVC rather than demonstrating irregular infiltration through adjacent liver parenchyma. Second, the paracaval caudate parenchyma remained uninvolved, arguing against direct trans-parenchymal spread. Third, the hepatocaval and adjacent retrohepatic connective tissues were indurated and involved by tumours, whereas the IVC wall itself was preserved, supporting preferential extension along connective tissue planes rather than vascular invasion.
The inability of preoperative imaging to clearly identify this pathway likely reflects the limitations of cross-sectional imaging in evaluating thin retrohepatic ligamentous structures. Nonetheless, retrospective review of diffusion-weighted magnetic resonance imaging (MRI) images demonstrated preservation of the paracaval caudate lobe with extension posterior to the IVC through the ligamentous plane (Fig. 5).
Diffusion-weighted MRI demonstrating tumour extension posterior to the IVC. Arrow indicating the hepatocaval ligament.
This case has important surgical implications. Surgeons managing caudate-origin iCCA should maintain a high index of suspicion for occult retrohepatic extension, particularly when the posterior tumour plane is not clearly defined preoperatively. Premature division of retrohepatic attachments may risk tumour violation and compromise oncologic margins. Careful intraoperative assessment of the hepatocaval plane and en bloc resection of involved retrohepatic ligamentous structures may therefore be necessary to achieve complete resection.
The present report is limited by its nature as a single case, and the true incidence of this dissemination pattern remains unknown. However, the concordance between intraoperative findings, gross specimen continuity, MRI review, and final pathology strongly supports the validity of this route of spread.
Conclusion
This case identifies a distinct pattern of retrocaval dissemination of caudate-origin iCCA along the hepatocaval ligament. This atypical route of spread was not evident on preoperative imaging and was only recognized intraoperatively, directly affecting surgical strategy. Awareness of this potential dissemination pathway may improve intraoperative decision making and help achieve complete oncologic resection in complex caudate lobe tumours.
Conflicts of interest
None declared.
Funding
None declared.
