An Elusive Cholangiocarcinoma Mimic: Primary Biliary Tuberculosis

Introduction: Extrapulmonary tuberculosis of the biliary tract is an elusive diagnosis, difficult to diagnosis given nonspecific symptoms and imaging studies. Historically, the diagnosis has been reliant on pathology, when technically feasible, but often requires surgical biopsy. We report here a case of primary biliary tuberculosis diagnosed with the assistance of cholangioscopic biopsies and endoscopic ultrasound (EUS) fine needle biopsies. Case Description/Methods: A healthy 49-year-old Filipino male presented to his primary care office for pruritus. His exam was unremarkable, but basic labs revealed a total bilirubin of 2.5 mg/dL; alkaline phosphatase of 273 U/L; and AST/ALT of 172/253 U/L, respectively. He underwent a Computed tomography scan, which raised concern for a mass arising from and obstructing the common hepatic duct. Magnetic Resonance Imaging confirmed a mass at the hepatic hilum consistent with Klatskin tumor with portal venous narrowing as well as additional masses in the caudate lobe and right lobe of the liver (Figure 1A and B). All lesions demonstrated irregular peripheral enhancement. The patient was, thus, referred for urgent Endoscopic Retrograde Cholangiopancreatography with cholangioscopy, notable for Bismuth IV stricture (Figure 1C) and frond-like/villous, fungating infiltrative intraductal lesion with hypervascularity (Figure 1D). Targeted biopsies were obtained with pathology showed acute and chronic histiocytic reaction, no malignancy. Bilateral transpapillary stenting was performed. Repeat ERCP was performed in light of fevers while admitted, again showing benign pathology. Because of benign pathology, an EUS was performed, notable for multiple, irregular, hypoechoic hepatic lesions (largest measuring 43 mm by 42 mm). Fine needle biopsies were performed of the largest mass as well as periportal lymph nodes, and cholangioscopic biopsies were again obtained with cytologic exam notable for histiocytes without malignancy. Cultures ultimately grew mycobacterium tuberculosis. Discussion: Hepatobiliary tuberculosis can present as biliary stricture(s) and mass(es), mimicking cholangiocarcinoma. Biliary tuberculosis is a particularly rare presentation of tuberculosis and is exceptionally rare as isolated extrapulmonary tuberculosis. Biliary tuberculosis is often reported as a diagnostic dilemma, as the diagnosis relies on tissue examination, and even the most advanced imaging modalities can lead to an incorrect diagnosis, as depicted in our case.Figure 1.: A and B) MRCP revealing mass at the hepatic hilum consistent with Klatskin tumor with portal venous narrowing as well as additional mass lesions noted in the caudate lobe and right lobe of the liver C) Cholangiogram notable for Bismuth IV stricture (Figure C) Cholangioscopy showing frond-like/villous, fungating infiltrative intraductal lesion with hypervascularity.