Cholangioscopy-guided diagnosis and management of biliary cast syndrome in a nontransplant patient

Abstract

Background and Aims

Biliary cast syndrome (BCS) in nontransplant patients is rare and diagnostically challenging. We demonstrate the role of single-operator cholangioscopy (SOC) in managing BCS in a patient with rheumatoid arthritis (RA) and identifying an occult, high-risk molecular marker.

Methods

A 54-year-old woman with RA presented with cholestatic liver dysfunction. After inconclusive imaging in a nondilated common bile duct, she underwent ERCP with SOC for diagnosis, multimodal cast removal, and targeted biopsy of the underlying mucosa.

Results

SOC directly visualized a branching biliary cast in a nondilated duct, leading to a definitive diagnosis. The cast was completely extracted using multimodal techniques. Biopsies of the inflamed mucosa revealed reactive atypical hyperplasia with loss of Smad4 expression on immunohistochemistry.

Conclusions

SOC is indispensable for diagnosing and managing BCS when imaging is inconclusive. This case links systemic inflammation to BCS and highlights the importance of SOC-guided biopsy to detect high-risk molecular changes, such as Smad4 loss in reactive hyperplasia, which warrants long-term surveillance.