Primary hepatic mucosa-associated lymphoid tissue lymphoma: a case report and literature review.

Primary hepatic mucosa-associated lymphoid tissue (MALT) lymphoma is an extremely rare disease. We herein describe the findings in a 74-year-old man with elevated liver enzyme levels. Dynamic computed tomography showed focal biliary dilation and atrophy in the posterior segment, while dynamic magnetic resonance images revealed a small, highly enhanced small mass located at the root of posterior branch of the biliary ducts. As the mass was not detected on abdominal ultrasonography, a biopsy could not be performed. Cholangiocellular carcinoma was suspected, and surgery was performed. However, the surgically resected hepatic tumor was a nodule of aggregated lymphocytes that formed a lymphoepithelial lesion. Immunohistochemical analysis revealed that the lymphoma cells were positive for CD20 and CD79a, but negative for CD3. No other lymphoid lesions were found during additional postoperative examinations. Therefore, the patient was diagnosed with primary hepatic MALT lymphoma. He was also diagnosed with Helicobacter pylori infection, and thus, pylorus eradication was performed. At the time of this report, the patient was free of disease for 2 years without any additional treatment. The present case contributed to the diagnosis and management of this rare disease, as previously published case reports described varying imaging features; it also suggested that preoperative diagnosis was often difficult without biopsy.