Primary hepatic low-grade B-cell lymphoma of the mucosa-associated lymphoid tissue type: a case report and review of the literature.

Primary hepatic lymphoma, mostly diffuse large B-cell lymphoma, is a rare disease. We describe an extremely rare case of low-grade B-cell lymphoma of the mucosa-associated lymphoid tissue (MALT) type occurring in the liver. A 61-year-old man with a history of hepatitis A presented with early gastric cancer and a liver mass. Needle biopsy of the liver tumor suggested low-grade B-cell lymphoma by histology and polymerase chain reaction of the immunoglobulin heavy chain gene. The tumor (3.4 x 2.8 x 2.4 cm) was completely resected from the anterior segment of the right lobe of the liver. Atypical lymphoid cells of small to intermediate size proliferated in the tumor, and lymphoepithelial lesions were recognized. Immunohistochemically, lymphoma cells were positive for CD20 and negative for CD5, CD10, and cyclin D1. Staging procedures showed no lymphoma lesion other than the liver tumor. Thus, the patient was diagnosed with low-grade hepatic marginal zone B-cell lymphoma of the MALT type. The patient has been followed up for 1.5 years since surgical resection with no recurrence. The clinicopathologic characteristics and management of this rare disease are discussed.