Pancreaticobiliary Maljunction and Neuroendocrine Carcinoma

Researchers describe an unusual case—a patient with a neuroendocrine carcinoma of the gallbladder accompanied by pancreaticobiliary maljunction—in the March issue of Clinical Gastroenterology and Hepatology.

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Tomonori Matsumoto et al examined a 58-year-old man with epigastric pain. Computed tomography (A) and fluoro-2-deoxy-d-glucose positron emission tomography (B) revealed angular diffuse thickening of the gallbladder wall (arrows) and multiple space-occupying lesions in the liver with abnormal uptake of fluoro-2-deoxy-d-glucose (arrowheads).

Endoscopic retrograde cholangiopancreatography performed for biliary obstruction by local lymphadenopathy and magnetic resonance cholangiopancreatography revealed an abnormally long common channel (arrowhead) without bile duct dilatation.

The authors determined that the patient had pancreaticobiliary maljunction (PBM)— a congenital anomaly defined as a junction of the pancreatic and bile ducts located outside the duodenal wall, usually forming a markedly long common channel. This led to reflux of pancreatic juices into the biliary tract; the patient had remarkably high levels of pancreatic enzymes in the bile, amylase, and lipase.

Percutaneous needle biopsy of the liver tumors and histologic analysis revealed proliferation of poorly differentiated carcinoma cells. The patient was diagnosed with poorly differentiated small neuroendocrine carcinoma (NEC) of the gallbladder with liver metastases, as well as PBM.

The patient received 6 courses of first-line chemotherapy with cisplatin and etoposide, which led to tumor regression. However, shortly afterward, the tumor progressed, and second-line chemotherapy with irinotecan was ineffective. The patient died of progressive disease 13 months after diagnosis.

Matsumoto et al explain that  high levels of pancreatic enzymes in bile can be used in diagnosis of PBM—a well-recognized risk factor for biliary tract cancer. PBM without bile duct dilatation has been associated with mucosal hyperplasia of the gallbladder and gallbladder carcinogenesis.

Most biliary tract cancers accompanied by PBM are adenocarcinomas, but there have been reported cases of NEC developing in the biliary tract of patients with PBM. However, neuroendocrine neoplasms, including NEC, rarely develop in the biliary tract, which lacks neuroendocrine cells.

Matsumoto et al say that further studies are needed to determine the origination of NEC in the biliary tract, but observations such as these provide evidence that chronic inflammation associated with PBM can lead to development of biliary NEC.

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