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case_images: Radiological findings of the bile duct lesion: (a, b) Axial and coronal contrast-enhanced computed tomography images showing irregular thickening of the distal bile duct wall. (c) Magnetic resonance cholangiopancreatography reveals stricture of the distal bile duct with dilatation of the proximal bile duct. (d) Positron emission-computed tomography reveals abnormal 18-fluorodeoxyglucose uptake at the site of the bile duct stricture. The maximum standardized uptake value is 32.29.
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case_images: Contrast-enhanced computed tomography (CT) revealed irregular thickening of the distal bile duct wall; however, no enlarged lymph nodes, pancreatic tumors, or other neoplastic lesions around the bile duct were apparent (Figure 1a-c, S1). Positron emission tomography-CT showed abnormal 18-fluorodeoxyglucose uptake at the site of the bile duct stricture, with a maximum standardized uptake value of 32.29 (Figure 1d).
case_images: Findings of endoscopic ultrasonography (EUS), endoscopic retrograde cholangiography (ERC), and intraductal ultrasonography (IDUS): (a, b) EUS reveals irregular thickening of the inner hypoechoic layer without the disappearance of the innermost thin hyperechoic layer (arrow). A hyperechoic mass indicating a bile duct stone is also detected (*). (c) ERC shows the distal bile duct stricture with a dilated proximal bile duct. (d) IDUS of the bile duct stricture site shows irregular thickening of the inner hypoechoic layer without the disappearance of the innermost thin hyperechoic layer, as seen on endoscopic ultrasonography.
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case_images: EUS revealed irregular thickening of the inner hypoechoic layer of the bile duct without the disappearance of the innermost thin hyperechoic layer (Figure 2a,b). Endoscopic retrograde cholangiography (ERC) showed a distal bile duct stricture with a dilated proximal bile duct (Figure 2c), and subsequently, IDUS revealed irregular thickening of the inner hypoechoic layer without disappearance of the innermost thin hyperechoic layer, as shown by EUS (Figure 3d). After six courses of R-CHOP, positron emission tomography-CT showed the disappearance of 18-fluorodeoxyglucose uptake in the bile duct, and contrast-enhanced CT and endoscopic retrograde cholangiography showed improvement in the bile duct stricture, (Figure S2).
case_images: Pathological findings of bile duct biopsy specimens: (a, b) Hematoxylin and eosin staining shows diffuse proliferation of large atypical lymphocytes with irregular nuclear shapes (a: x100, b: x400). (c, d) Immunohistochemical staining shows that the lymphocytes were positive for CD20 and negative for CD3 (c: CD20 x400, d: CD3 x400).
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case_images: Endoscopic retrograde cholangiography (ERC) showed a distal bile duct stricture with a dilated proximal bile duct (Figure 2c), and subsequently, IDUS revealed irregular thickening of the inner hypoechoic layer without disappearance of the innermost thin hyperechoic layer, as shown by EUS (Figure 3d). Pathological findings (Figure 3a-d) revealed a diffuse proliferation of large atypical lymphocytes with irregular nuclear shapes.