Endoscopic Ultrasound-Guided Diagnosis of Gallbladder Mixed Neuroendocrine Non-Neuroendocrine Tumor With an Anomalous Pancreaticobiliary Junction

Mixed neuroendocrine non-neuroendocrine neoplasms are exceedingly rare tumors, especially those of gallbladder origin. Anomalous pancreaticobiliary junction is an uncommon congenital abnormality that can predispose various types of hepatobiliary malignancies. We present an unusual case of a 46-year-old woman with anomalous pancreaticobiliary junction who presented to the emergency department with nausea, vomiting, and right upper quadrant pain. Magnetic resonance imaging revealed a gallbladder mass concerning for primary malignancy and liver lesions. Endoscopic ultrasound and fine-needle biopsy were valuable diagnostic tools used to sample the gallbladder, liver lesions, and common hepatic duct under one minimally invasive procedure. Pathology showed a gallbladder mixed neuroendocrine non-neuroendocrine neoplasms, with neuroendocrine components in the liver and adenocarcinoma components in the common hepatic duct.