Primary Hepatic Mucosa-Associated Lymphoid Tissue Lymphoma and Primary Biliary Cholangitis: A Case Report of a Rare Association.

Introduction: Primary hepatic mucosa-associated lymphoid tissue (MALT) lymphoma is an exceedingly rare subtype of extranodal marginal zone B-cell lymphoma within the spectrum of non-Hodgkin lymphomas. Chronic inflammatory and autoimmune conditions are recognized risk factors for lymphomagenesis; however, the association between primary hepatic MALT lymphoma and primary biliary cholangitis (PBC) has been rarely reported. Case Presentation: We report the case of a 50-year-old woman with a 9-year history of non-cirrhotic PBC, treated with ursodeoxycholic acid and with only partial biochemical response, who was referred for further evaluation of focal liver lesions detected during follow-up. Magnetic resonance imaging revealed two small right-lobe nodules with arterial phase enhancement and apparent delayed washout, raising suspicion of hepatocellular carcinoma. In the absence of advanced chronic liver disease, a liver biopsy was performed. Local pathology showed an atypical lymphoid infiltrate not compatible with hepatocellular carcinoma, and expert hematopathology review favored a low-grade B-cell lymphoma, suggestive of primary hepatic extranodal marginal zone lymphoma of MALT type. Comprehensive staging excluded extrahepatic involvement. Given the indolent course and absence of disseminated disease, a watchful waiting strategy was adopted. No disease progression has been documented after 8 years of follow-up. Discussion/Conclusion: This case highlights a rare association between primary hepatic MALT lymphoma and PBC in an asymptomatic, immunocompetent patient without cirrhosis. It underscores the importance of considering alternative diagnoses and performing liver biopsy when evaluating focal liver lesions in non-cirrhotic patients with autoimmune liver disease, particularly when imaging findings are suspicious but not sufficient for a definitive non-invasive diagnosis. Chronic immune-mediated inflammation may have contributed to the pathogenesis of this rare lymphoma.