Primary hepatic mucosa-associated lymphoid tissue lymphoma mimicking hepatocellular carcinoma in a patient with chronic hepatitis B: a case report.

Primary hepatic lymphoma is a rare disease, and primary hepatic mucosa-associated lymphoid tissue (MALT) lymphoma accounts for only 0.3% of all primary hepatic lymphomas. Herein, we report a case of primary hepatic MALT lymphoma in a male patient in his mid-40 s with chronic hepatitis B infection. The patient visited our department for further examination of a hepatic nodule initially visualized through abdominal pelvic computed tomography (CT). Based on imaging studies and elevated levels of tumor markers, the tumor was suspected to be hepatocellular carcinoma. A laparoscopic inferior sectionectomy (segment 5 and 6) was performed, and immunohistochemical staining revealed that the tumor was positive for CD20, B-cell lymphoma 2, pan-cytokeratin (CK), and CK19 markers. Pathological findings revealed it to be a primary hepatic MALT lymphoma. After surgery, bone marrow biopsies and fluorodeoxyglucose-positron emission tomography integrated with CT scanning confirmed that there was no other involvement. The patient did not receive chemotherapy, and there was no recurrence during the 24-month follow-up period. Hepatocellular carcinoma is the most common malignancy in patients with chronic hepatitis B, but rare tumors such as primary MALT lymphoma can also occur, so a careful approach is required for their differentiation.