# Unique endoscopic features of primary biliary diffuse large B‐cell lymphoma: A case report with literature review (with video)

## TL;DR

A 67-year-old man was diagnosed with a rare bile duct lymphoma using endoscopic techniques and biopsies, leading to successful treatment.

## Contribution

Highlights unique endoscopic features and diagnostic approach for primary biliary diffuse large B-cell lymphoma.

## Key findings

- Endoscopic ultrasonography showed irregular thickening of the bile duct without disappearance of the innermost layer.
- Repeated biopsies confirmed diffuse large B-cell lymphoma in the bile duct.
- Systemic chemotherapy led to significant improvement in bile duct stricture and lymphoma symptoms.

## Abstract

A 67‐year‐old man visited our hospital complaining of dark‐colored urine and upper abdominal pain. Magnetic resonance cholangiopancreatography showed stricture of the distal bile duct, and contrast‐enhanced computed tomography showed irregular thickening of the distal bile duct wall. However, no enlarged lymph nodes, pancreatic tumors, or other neoplastic lesions were apparent around the bile duct. Endoscopic ultrasonography and intraductal ultrasonography showed irregular thickening of the inner hypoechoic layer without the disappearance of the innermost thin hyperechoic layer. On the basis of these findings, we considered that the bile duct lesion was of non‐epithelial origin. Thus, we repeatedly performed bile duct biopsies from the same site under fluoroscopy to obtain a sample of the submucosal tissue. The pathological diagnosis was diffuse large B‐cell lymphoma, and the patient received systemic chemotherapy (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone). After six courses of rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone, positron emission tomography‐computed tomography showed the disappearance of 18‐fluorodeoxyglucose uptake in the bile duct and endoscopic retrograde cholangiography showed improvement of the bile duct stricture. Endoscopic findings and repeated biopsies were useful in making the diagnosis of primary biliary diffuse large B‐cell lymphoma.