S5849 Primary Liver Involvement in Mantle Cell Lymphoma: A Diagnostic Trap

Introduction: Mantle cell lymphoma (MCL) is an uncommon, aggressive B-cell non-Hodgkin lymphoma that typically presents with lymphadenopathy, splenomegaly, and gastrointestinal (GI) tract involvement, most often as multiple lymphomatous polyps. In contrast, hepatic metastases more commonly arise from GI adenocarcinomas, breast, lung, or pancreatic primaries. We present a case of MCL initially presenting with tumor lysis syndrome (TLS) and cholestatic liver injury, mimicking hepatobiliary malignancy, to highlight diagnostic and therapeutic considerations relevant to gastroenterologists. Case Description/Methods: A 90-year-old man with coronary artery disease, prior coronary artery bypass graft, and known pancreatic cysts presented with abdominal pain, nausea, and vomiting. He was discharged with a presumed diagnosis of chronic lymphocytic leukemia and a splenic infarct. He re-presented several days later with worsening jaundice, anorexia, weakness, and a shuffling gait. Vitals revealed hypotension and mild hypoxia. Laboratory evaluation showed white blood cell count 109.5 × 10⁹/L, creatinine 3.1 mg/dL, potassium 9.1 mmol/L, uric acid 16.2 mg/dL, ammonia 82 µmol/L, total bilirubin 19.7 mg/dL (direct 12.6), alkaline phosphatase 472 U/L, and aspartate aminotransferase 59 U/L. Computed tomography and MRI/MRCP demonstrated hepatosplenomegaly, splenic infarcts, gallbladder wall thickening with cholelithiasis, and no biliary ductal dilation. Given concern for infiltrative disease, bone marrow flow cytometry was performed and revealed a CD5+ (bright), CD23+, FMC7+, CD10−, kappa-restricted mature B-cell population consistent with MCL. Liver biopsy confirmed diffuse infiltration by MCL with a high proliferative index (Ki-67: 70–80%). The patient developed spontaneous TLS requiring ICU-level care, vasopressors, CRRT, and rasburicase. Due to poor functional status, curative therapy was deferred, and palliative care was initiated. He ultimately died from multi-organ failure. Discussion: This case underscores the importance of considering infiltrative lymphoma in patients presenting with hepatosplenomegaly, atypical cholestasis, and no clear obstructive process. For gastroenterologists, early liver biopsy can be pivotal in differentiating hematologic malignancy from primary hepatobiliary cancer when imaging is inconclusive. Although hepatic MCL is rare, it can present with fulminant disease. Timely recognition may expedite diagnosis and guide appropriate management, especially in elderly or frail patients, where treatment must be individualized.