Primary Malt Lymphoma of the Common Bile Duct
A 79-year-old male presented with a four-week history of vague, generalized abdominal discomfort and progressive jaundice. He complained of pruritus and dark urine, although he showed no weight loss, febrile sensation or chills. He had no history of biliary stone disease or prior abdominal surgery. Physical examination revealed jaundice with icteric sclera. Laboratory studies showed cholestasis with a total bilirubin of 2.2 mg/dL (normal, < 1.0 mg/dL), direct bilirubin of 1.5 mg/dL (normal, < 0.3 mg/dL), aspirate amino transferase of 141 IU/L (normal, < 40 IU/L), alanine transferase of 190 IU/L (normal, < 56 IU/L), and alkaline phosphatase of 284 IU/L (normal, < 147 IU/L). Serum tumor markers, including CEA and CA 19-9, were not elevated.\nComputed tomography (CT) examination was performed on a 16-multidetector CT system (LightSpeed 16; GE Healthcare, Milwaukee, WI, USA) with triphasic dynamic imaging. The arterial-, portal-, and delayed-phase images were obtained using a 25-s, 72-s, and 180-s delay, respectively, after intravenous injection of 2.5 mL/kg of iopromide (Ultravist 370; Bayer Schering Pharma, Berlin, Germany) at a rate of 3 mL/s. The CT parameters were beam collimation of 16 × 1.25 mm, beam pitch of 0.938, 120 kV, 200 mAs, and slice thickness of 3 mm. CT revealed diffuse, irregular wall thickening of the CBD, including the intrapancreatic portion of the CBD, with minimal dilatation of the common hepatic duct (CHD) and the intrahepatic duct (IHD) (). The thickened ductal wall showed relatively homogeneous enhancement with isoattenuation compared to the liver parenchyma on the arterial, portal, and delayed phases. A small lymph node with a short-axis diameter of 8 mm was observed within the hepatoduodenal ligament. Magnetic resonance imaging (MRI) with MR cholangiography using a 1.5 T scanner (Magnetom Avanto; Medical Solutions, Erlangen, Germany) depicted ductal wall thickening with slight hypointensity relative to the liver parenchyma on T1-weighted images (TR/TE, 164/4.5; flip angle, 70°; FOV, 350 × 250; slice thickness, 6 mm) and slight hyperintensity on T2-weighted images (TR/TE, 1900/88; echo train length, 13; flip angle, 150°; FOV, 350 × 250; slice thickness, 6 mm). Diffusion-weighted images with a b-value of 800 showed heterogeneous hyperintensity in the CBD (). Although the distal CBD lumen was relatively maintained, the entire CBD exhibited irregular luminal narrowing on MR cholangiography using single-shot rapid acquisition with relaxation enhancement sequence (TR/TE, infinite/1000; echo train length, 256; FOV, 250 × 250; slice thickness, 40 mm) (). The CHD and IHD showed mild dilatation, which was in agreement with the CT findings.\nIn order to relieve the patient's obstructive jaundice, we performed endoscopic retrograde cholangiopancreatography (ERCP) with plastic biliary drainage catheter placement. ERCP revealed diffuse, irregular luminal narrowing of the entire CBD, including the intrapancreatic portion, with diffuse, mild dilatation of the upstream biliary tree (). ERCP also showed an out-pouching, diverticulum-like lesion in the proximal CBD.\nA preoperative diagnosis of cholangiocarcinoma involving the CBD was made, and the patient underwent pyloruspreserving pancreaticoduodenectomy. Grossly, the CBD was found to be diffusely thickened (). No significantly enlarged regional lymph nodes were found, although routine lymph node dissection was performed. Histologic examination under light microscopy revealed dense and diffuse infiltration of atypical lymphoid cells and the formation of lymphoid follicles within the CBD walls (). On immunohistochemical staining, the tumor exhibited CD20 positivity and CD3 negativity. Ki-67 was almost negative with less than 1% positivity. Lambda, kappa, IgG, and IgG4 were all noncontributory. A final pathology diagnosis of low-grade B-cell lymphoma of the MALT type arising from the CBD was made. Of the 15 dissected lymph nodes, no foci of lymphoma involvement were discovered.