A Cause of Unresectable Gallbladder Cancer: Pancreaticobiliary Maljunction Masked by Adenomyomatosis

What is it about?

The two presented cases were initially diagnosed with adenomyomatosis of the gallbladder (ADM) via conventional transabdominal ultrasound (US) and monitored under this diagnosis for several years. Since no significant changes during their annual health check-ups were observed and they remained asymptomatic, further investigations (e.g., MRCP: magnetic resonance cholangiopancreatography, EUS: endoscopic ultrasound, or ERCP: endoscopic retrograde cholangiopancreatography) were not conducted. Following the onset of symptoms and the subsequent detection of pancreaticobiliary maljunction (PBM) with a non-dilated extrahepatic bile duct (EBD), Case 1 underwent successful prophylactic laparoscopic cholecystectomy before developing gallbladder carcinoma (GBC). In contrast, asymptomatic Case 2 (Figure A and B) was incidentally diagnosed with unresectable GBC during an annual health check-up. ERCP subsequently confirmed the presence of PBM with a non-dilated EBD, but the detection of PBM in this asymptomatic ADM patient occurred too late. As a result, she was not considered a candidate for prophylactic laparoscopic cholecystectomy and ultimately died of far-advanced GBC arising in ADM associated with PBM and a non-dilated EBD. FIGURE (A) 1st annual check-up; Ultrasound (US) reveals a diffusely, mildly thickened gallbladder wall with a granular surface mucosa (arrowheads) and comet-tail artifacts (arrow) in the body. (B) 3 years after; US reveals far-advanced gallbladder carcinoma (open triangle: transmural and heterogeneous wall thickening of the gallbladder) with direct invasion into the liver (black arrowhead: ruptured outermost hyperechoic layer of the gallbladder) and hepatic metastases (white arrows: ill-defined heterogeneous hypoechoic lesions).

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Photo by Vincent van Zalinge on Unsplash

Photo by Vincent van Zalinge on Unsplash

Why is it important?

ADM is histologically characterized by Rokitansky-Aschoff sinus (RAS) proliferation, smooth muscle hypertrophy, and fibrosis of the gallbladder and is generally considered a benign condition. Many studies have reported GBC associated with either PBM or ADM, while a dozen or so studies have recently documented ADM associated with PBM. While the prevalence of ADM associated with PBM remains unclear, we agree with the hypothesis that chronic stimulation caused by pancreatic juice reflux due to PBM is one of the pathogenic mechanisms of ADM. Additionally, the fact that PBM, which can be latent in ADM, rarely plays a role in the progression from ADM to GBC has not been sufficiently emphasized. Although a few studies have documented that asymptomatic ADM associated with PBM and a non-dilated EBD is a recognized risk factor for GBC and an indication for cholecystectomy, regardless of ADM subtype, the English literature has rarely reported GBC associated with both PBM and ADM. Therefore, this case report, especially Case 2, is crucial.

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