Double primary biliary malignancy: synchronous gallbladder carcinoma and extrahepatic cholangiocarcinoma in a Whipple specimen—a case report and literature review

Introduction

Synchronous primary carcinomas (SPCs) of the gallbladder (GB) and extrahepatic bile duct (EBD) constitute an exceptional diagnostic entity within biliary tract oncology, accounting for less than 0.1% of all malignancies in this region (1). Since the first documented case, fewer than 20 histologically verified instances have been reported in MEDLINE-indexed literature spanning from 1960 to 2023 (2). The profound clinical significance of this rarity lies in the substantial diagnostic challenge it poses; these dual tumors are often misinterpreted as metastatic disease from a single primary site. Such misclassification can erroneously preclude patients from potentially curative surgical intervention, relegating them to palliative systemic therapy with a markedly poorer prognosis (3).

The standard diagnostic approach for suspected biliary malignancies begins with clinical evaluation of obstructive jaundice, followed by imaging studies including ultrasonography, contrast-enhanced computed tomography (CECT), and magnetic resonance cholangiopancreatography (MRCP) to delineate biliary anatomy and identify multifocal lesions. However, even with advanced imaging, distinguishing between metastatic spread and synchronous primaries remains challenging. Factors contributing to misdiagnosis include: (I) morphological similarity between biliary adenocarcinomas, (II) failure to sample the GB during routine bile duct cancer resections, (III) incomplete immunohistochemical (IHC) workup, and (IV) low clinical suspicion due to extreme rarity of synchronous presentations (3,4).

The diagnostic cornerstone for SPCs remains the Warren–Gates criteria, which require: (I) histological confirmation of malignancy in each site, (II) geographical separation by normal intervening tissue, and (III) the exclusion of one being a metastasis of the other (4). Advances in cross-sectional imaging and IHC techniques have improved recognition, yet the true incidence is likely underestimated. This is partly because routine histological sampling of the GB is often omitted during resection for bile duct cancer (5).

The etiopathogenesis of synchronous biliary malignancies is multifaceted. Anomalous pancreaticobiliary duct junction (APBDJ), leading to chronic reflux of pancreatic juice, is a well-established risk factor for the development of biliary tract cancers and has been associated with several reported cases of double primaries (6). However, a subset of cases, including the one presented here, occurs in the absence of APBDJ, supporting the alternative hypothesis of “field cancerization” or “field effect”. This theory posits that prolonged exposure of the entire biliary epithelium to common carcinogenic insults (e.g., chronic inflammation, cholestasis, specific environmental toxins) induces independent genetic alterations in spatially distinct areas, culminating in multiple synchronous primary tumors (7,8).

This case report contributes to this sparse literature by detailing a meticulously investigated instance of pathologically proven synchronous GB and distal common bile duct (CBD) adenocarcinomas. We emphasize the diagnostic algorithm, the decisive role of comparative immunohistochemistry (IHC), the critical steps in perioperative management, and provide an updated review of therapeutic strategies and outcomes from comparable cases. We present this article in accordance with the CARE reporting checklist (available at https://apc.amegroups.com/article/view/10.21037/apc-25-14/rc).

Case presentation

Clinical history and presentation

A 73-year-old female, with no significant past medical history, presented to our gastroenterology outpatient department with a three-week history of progressive, painless jaundice, associated with pruritus, dark urine, and pale stools. She reported an unintentional weight loss of approximately 7 kg (12% of her body weight) over the preceding two months. There was no history of fever, abdominal pain, or prior biliary surgery. Physical examination revealed deep icterus and scratch marks on the extremities. Abdominal examination was unremarkable without palpable masses or organomegaly.

Diagnostic work-up

Laboratory investigations revealed a cholestatic pattern: total bilirubin 18.2 mg/dL (direct 14.5 mg/dL), alkaline phosphatase 850 U/L, gamma-glutamyl transferase 620 U/L, and serum albumin 2.8 g/dL. Tumor marker carbohydrate antigen 19-9 (CA 19-9) was significantly elevated at 680 U/mL (normal <37 U/mL).

Imaging studies were initiated. Abdominal ultrasonography identified a focal, irregular thickening of the GB wall at the fundus measuring 8 mm and a distal CBD stricture with upstream intrahepatic biliary radical dilatation (IHD up to 12 mm). Subsequent CECT of the abdomen (Figure 1A,1B) confirmed these findings, demonstrating a heterogeneously enhancing, circumferential soft-tissue lesion in the distal CBD measuring 2.3 cm × 1.8 cm, causing significant proximal biliary dilatation (CBD 15 mm). A separate, enhancing focal wall thickening at the GB fundus, measuring 10 mm, was noted. No vascular invasion, liver metastases, or significant lymphadenopathy were apparent. MRCP (Figure 1C) elegantly delineated two discontinuous lesions: a 1.5 cm long tight stricture in the distal CBD and a 2.5 cm mass at the GB fundus, with a normal intervening cystic duct and common hepatic duct. The spatial separation and distinct morphological characteristics raised a strong radiological suspicion of synchronous primary tumors.

Figure 1 Preoperative imaging findings. (A,B) CECT of the abdomen showing a heterogeneously enhancing circumferential soft-tissue lesion involving the distal common bile duct (arrow) with proximal biliary dilatation, along with focal irregular wall thickening at the gallbladder fundus. (C) MRCP demonstrating two discontinuous lesions—a tight distal CBD stricture and a separate gallbladder fundal mass—with a normal intervening cystic duct and common hepatic duct, suggestive of synchronous primary tumors. CBD, common bile duct; CECT, contrast-enhanced computed tomography; MRCP, magnetic resonance cholangiopancreatography.

Multidisciplinary team discussion and preoperative optimization

The case was reviewed in a dedicated hepatobiliary-pancreatic multidisciplinary tumor board comprising surgical oncologists, medical oncologists, radiologists, pathologists, and interventional gastroenterologists. The consensus was that both lesions were potentially resectable (R0 resection deemed feasible) and represented likely synchronous primaries rather than metastatic disease. Given the patient’s profound hyperbilirubinemia (bilirubin >15 mg/dL), which significantly increases the risk of postoperative hepatic dysfunction and morbidity, preoperative biliary drainage was mandated (9).

The patient underwent endoscopic retrograde cholangiopancreatography (ERCP), which confirmed the distal CBD stricture. A plastic biliary stent was successfully deployed. Concurrently, she received intensive nutritional support with protein supplements. Over the ensuing two weeks, her biochemical parameters improved markedly: bilirubin decreased to 4.1 mg/dL, albumin increased to 3.3 g/dL, and her general condition optimized, clearing her for major surgery.

Surgical management

Surgery commenced with a diagnostic staging laparoscopy, which revealed no occult peritoneal or liver surface metastases. This was followed by an open procedure. A standard pancreatoduodenectomy (Whipple procedure) was performed, extended to include a en bloc cholecystectomy and a 2 cm wedge resection of liver segments IVb/V to ensure a clear hepatic margin for the GB tumor. Intraoperative frozen section analysis of the proximal (hepatic duct) bile duct margin was negative for malignancy. The surgical procedure lasted 6.5 hours and required one unit of packed red blood cell transfusion. A feeding jejunostomy tube was placed for early postoperative enteral nutrition.

Postoperative course and adjuvant therapy

The patient’s initial recovery was complicated by a superficial surgical site infection, which was managed with local wound care and antibiotics. Enteral feeding via the jejunostomy was initiated on postoperative day (POD) 1. She was advanced to a soft oral diet by POD 7 and was discharged in a stable condition on POD 10. The final histopathology report, confirming synchronous primaries with high-risk features (node positivity, perineural invasion), guided adjuvant therapy. After an uneventful recovery period, she received six cycles of adjuvant chemotherapy with gemcitabine and cisplatin, commencing eight weeks post-surgery. At her most recent follow-up, 12 months post-resection, she remains clinically well, with normal liver function tests, a CA 19-9 level of 22 U/mL, and surveillance computed tomography (CT) scans showing no evidence of disease recurrence.

Pathological findings

Gross examination

The hepatopancreatoduodenectomy specimen was received en bloc. Careful dissection revealed two grossly distinct tumors (Figure 2):

• GB tumor: a solid, white, firm, infiltrative mass measuring 2.5 cm × 2.0 cm× 1.0 cm located in the fundus and body. The tumor involved the full thickness of the wall but was separated from the liver bed by a 0.4 cm rim of uninvolved soft tissue.
• Distal CBD tumor: an ulceroinfiltrative, grey-white tumor measuring 4.0 cm × 3.0 cm × 2.0 cm, located 1.8 cm distal to the GB neck/cystic duct junction. The tumor encircled and stenosed the CBD lumen.

Figure 2 Gross appearance of the Whipple specimen. Gross photograph of the hepatopancreatoduodenectomy (Whipple) specimen showing two anatomically distinct tumors: a gallbladder fundal tumor (black arrow) and an ulceroinfiltrative distal common bile duct tumor (white arrow), separated by intervening normal tissue (arrowhead), supporting independent primary origins.

Histopathology

Microscopic examination of both lesions confirmed moderately differentiated adenocarcinoma (Grade 2). The morphological features, however, were distinct in their invasive patterns (Table 1).

• Distal CBD carcinoma: the tumor was staged as pT3. It showed transmural invasion through the bile duct wall into the surrounding periductal adipose tissue (Figure 3A). Extensive lymphovascular invasion (LVI) and perineural invasion (PNI) were prominent. The tumor also directly invaded the adjacent pancreatic parenchyma to a depth exceeding 0.5 cm.
• GB carcinoma: the tumor was staged as pT2b. It demonstrated invasion into the perimuscular connective tissue but not through the serosa. Focal LVI and PNI were identified (Figure 3B).
• Lymph node status: the lymphatic drainage patterns were distinct and supportive of independent primaries.
• GB basin (cystic duct and pericholedochal nodes): 2 out of 7 lymph nodes were positive for metastatic carcinoma, with microscopic extranodal extension noted.
• CBD/pancreaticoduodenal basin: 14 out of 16 lymph nodes were positive, with the largest metastatic deposit measuring 1.2 cm.

Figure 3 Histopathological features of distal common bile duct tumor. Photomicrographs showing moderately differentiated adenocarcinoma of the distal common bile duct. (A) Low-power view demonstrating infiltrative glandular architecture (H&E, ×40). (B) Higher magnification showing malignant glands embedded in desmoplastic stroma (H&E, ×200). (C) Tumor glands with luminal mucin production (H&E, ×400). Scale bars represent 500 µm (A), 100 µm (B), and 50 µm (C). H&E, hematoxylin and eosin.

Surgical margins: all resection margins were histologically free of tumor (R0 resection). The detailed margin assessment is provided in Table 2.

IHC

IHC was instrumental in establishing the synchronous primary nature of the tumors (Figure 4). Both tumors exhibited a biliary immunophenotype: positive for CK7 and MUC1, and negative for CK20 and CDX2 (excluding intestinal differentiation or metastatic colorectal carcinoma). The discriminatory marker was MOC31 (EpCAM): it was completely negative in the GB adenocarcinoma but showed strong, diffuse membranous positivity in the distal CBD adenocarcinoma (Figure 5A-5H). This discordant immunoprofile provided conclusive evidence against a metastatic relationship.

Figure 4 Histopathological features of gallbladder tumor. Photomicrographs of gallbladder adenocarcinoma. (A) Tumor infiltrating the perimuscular connective tissue without serosal breach (H&E, ×40). (B) Higher magnification showing irregular malignant glands with nuclear pleomorphism and desmoplastic response (H&E, ×200). Scale bars represent 500 µm (A) and 100 µm (B). H&E, hematoxylin and eosin.

Figure 5 Immunohistochemical findings. Immunohistochemical staining demonstrating differential expression profiles in synchronous biliary tumors. (A-C) Distal common bile duct adenocarcinoma showing strong membranous positivity for CK7 and MUC1. (D) Negative staining for CK20. (E,F) Strong membranous positivity for MOC31 in the distal bile duct tumor. (G,H) Gallbladder adenocarcinoma showing complete negativity for MOC31, supporting distinct clonal origin (IHC, ×200). Scale bars represent 100 µm. IHC, immunohistochemical.

Final Pathological Staging (AJCC 8th Edition)

• GB carcinoma: pT2bN1M0 (Stage IIIB);
• Distal CBD (cholangiocarcinoma): pT3N2M0 (Stage IIIA).

All procedures performed in this study were in accordance with the ethical standards of the institutional research committee of UPUMS, Saifai and with the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Discussion

The presentation of synchronous primary adenocarcinomas in the GB and EBD, as documented in this report, is a pinnacle of diagnostic complexity in hepatobiliary pathology. Our case unequivocally satisfies the Warren-Gates criteria, providing a classic template for distinguishing this entity from metastatic disease (4).

Diagnostic challenges and the role of IHC

The principal diagnostic dilemma lies in differentiating between a single primary bile duct cancer with GB metastasis (or vice versa) and two independent primaries. Routine histology is often insufficient, as both entities are typically adenocarcinomas with similar morphology. This is where systematic IHC profiling becomes indispensable. Biliary adenocarcinomas commonly express CK7 and are negative for CK20 (10). Markers like MUC1 are associated with a biliary phenotype (11,12), while CDX2 negativity helps rule out a gastrointestinal primary. In our case, the differential expression of MOC31 (EpCAM) was the key discriminant. MOC31 is a glycoprotein frequently expressed in adenocarcinomas of various origins, including cholangiocarcinoma, but its expression can be heterogeneous. The stark contrast—complete negativity in the GB tumor versus strong positivity in the CBD tumor—provided robust evidence of divergent clonal origins, a finding consistent with several other reported cases (2,13). This underscores the necessity of employing a tailored IHC panel (e.g., CK7, CK20, CDX2, MUC1, MOC31, and potentially site-specific markers like SATB2 or TFF1) in such scenarios.

Etiopathogenesis: field cancerization

While APBDJ is a known predisposing factor for biliary tract carcinogenesis, its absence in our case and in the series reported by Rajekar et al. (14) points toward an alternative mechanism: field cancerization. This concept, originally described in head and neck and lung cancers (15,16), suggests that prolonged exposure of a wide mucosal field to carcinogens leads to independent, clonally distinct premalignant changes at multiple sites (7,8). The entire biliary epithelium, from the intrahepatic ducts to the ampulla, can be considered a “field” susceptible to injury from chronic inflammation, biliary stasis, and environmental toxins. This model elegantly explains the development of synchronous or metachronous primaries without a direct anatomical connection like APBDJ. Further molecular studies analyzing mutational profiles (e.g., KRAS, TP53, SMAD4, ARID1A) (17) in both tumors from such cases could provide stronger genomic evidence for or against a common clonal origin.

Therapeutic considerations and surgical strategy

Complete surgical resection (R0) is the only potentially curative treatment for synchronous biliary primaries, as evidenced by the hepatopancreatoduodenectomy performed here (18). The choice of surgical procedure depends on the location of the tumors. For a distal CBD tumor and a GB tumor, a Whipple procedure with cholecystectomy and limited hepatic wedge resection is often appropriate, as it allows en bloc removal of both primary sites and their regional lymph node basins. The high incidence of lymph node metastasis (57% in aggregated literature) and PNI (43%) underscores the aggressive biology of these tumors and strongly supports the use of adjuvant chemotherapy (19). The current standard of care, based on the BILCAP and PRODIGE-12 trials, is adjuvant capecitabine for biliary tract cancers, though gemcitabine-cisplatin is also widely used (12,16). Our patient received the latter regimen based on multidisciplinary consensus and tolerability.

Prognosis and follow-up

The prognosis for patients with synchronous biliary primaries remains guarded, primarily dictated by the highest stage among the tumors and the presence of high-risk features like node positivity, perineural invasion, and margin status. A literature review (Table 3) suggests that patients who undergo successful R0 resection have a median survival of approximately 23 months, which is comparable to, if not slightly worse than, single-site advanced biliary cancers (2,13). This highlights the necessity for vigilant, long-term postoperative surveillance with serial imaging and tumor marker assessment.

Strengths and limitations

The principal strength of this report lies in its comprehensive diagnostic workup, incorporating detailed radiology, meticulous histopathology with extensive IHC correlation, and adherence to a multidisciplinary management protocol. The provision of 12-month follow-up data adds clinical relevance. The primary limitation is inherent to its design as a single case report, which precludes broad generalizations. Furthermore, molecular profiling of both tumors, while desirable, was not performed and represents an avenue for future research in similar cases.

Conclusions

This case adds to the exceedingly sparse literature on synchronous GB and EBD adenocarcinomas. It serves as a compelling reminder of several key principles in hepatobiliary oncology:

• Synchronous primary biliary malignancies, though rare, must be considered in the differential diagnosis of multifocal biliary lesions to avoid the critical error of mislabeling them as inoperable metastatic disease.
• A definitive diagnosis hinges on meticulous histopathological examination reinforced by a strategic IHC panel, with markers like MOC31 providing crucial discriminatory value.
• The concept of field cancerization offers a plausible explanation for the pathogenesis of such tumors in the absence of anatomical anomalies like APBDJ.
• A curative outcome is attainable through aggressive, well-planned surgical resection guided by a multidisciplinary team, followed by appropriate adjuvant therapy.
• Given the aggressive tumor biology, patients require diligent long-term surveillance.

We propose a simplified diagnostic algorithm (Figure 6) to aid clinicians and pathologists in navigating similar challenging presentations, with the goal of optimizing patient management and outcomes.

Figure 6 Proposed diagnostic algorithm for suspected synchronous biliary primaries. Flowchart illustrating the stepwise diagnostic approach from initial presentation through imaging, multidisciplinary discussion, preoperative optimization, surgical resection, histopathological evaluation with immunohistochemistry, and final diagnosis with adjuvant therapy and surveillance. This algorithm aims to minimize misdiagnosis and guide optimal management of synchronous biliary malignancies. CA 19-9, carbohydrate antigen 19-9; CBD, common bile duct; CT, computed tomography; ERCP, endoscopic retrograde cholangiopancreatography; GB, gallbladder; IHC, immunohistochemical; MDT, multidisciplinary team; MRCP, magnetic resonance cholangiopancreatography; US, ultrasound.

Acknowledgments

The authors would like to thank the technical staff of the Department of Pathology, UPUMS, Saifai, for their excellent support in tissue processing and immunohistochemistry.

Footnote

Reporting Checklist: The authors have completed the CARE reporting checklist. Available at https://apc.amegroups.com/article/view/10.21037/apc-25-14/rc

Peer Review File: Available at https://apc.amegroups.com/article/view/10.21037/apc-25-14/prf

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://apc.amegroups.com/article/view/10.21037/apc-25-14/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 research committee of UPUMS, Saifai and with the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the patient for publication of this case report 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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