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

Background: The prevalence of primary hepatic mucosa-associated lymphoid tissue (MALT) lymphomas is extremely low. Here, we describe a case of this disease misdiagnosed as hepatocellular carcinoma (HCC) and review relevant literature to prevent future misdiagnoses. Case presentation: a 58-year-old woman complained about abdominal pain for more than four months. About two months prior, she came to our hospital with elevated levels of HBV DNA and positive HBsAg and HBcAb. After two months of entecavir treatment, HBV DNA decreased to a normal level. She returned to the hospital with worsened abdominal pain for over a month. Magnetic resonance imaging and systemic positron emission tomography-computed tomography identified two nodes in the liver, and she was diagnosed with HCC. The patient then underwent a laparoscopic hepatectomy. Microscopic examination showed a diffuse infiltrate of small-to-medium-sized lymphocytes and lymphoepithelial lesions. Immunohistochemical staining showed that most of the lymphoid cells were strongly positive for CD20, CD79a, BCL2, IgM and weakly positive for IgD, while negative for CD3, CD10, BCL6, MUM1, CD43, CD5, cyclin D1, CD23, CD30, and PD1. The Ki-67 index of lymphoid cells was 5%. Further pathologic analysis confirmed the diagnosis of primary hepatic MALT lymphoma. The patient received antiviral treatment and recovered well with no sign of relapse for 17 months. Conclusions: Primary hepatic MALT lymphoma is an uncommon disease that is difficult to diagnose and has no widely accepted treatment. Surgical resection is a good choice for both diagnosis and local therapy, and strict follow-up of the patient is essential.