Primary hepatic low-grade B-cell lymphoma of MALT-type associated with Helicobacter pylori infection.

Primary marginal zone B-cell lymphoma of mucosa associated tissue (MALT) type in the liver is extremely rare, and the etiology of this disease is yet to be clarified. We present the first report of a primary hepatic low-grade lymphoma of MALT-type associated with Helicobacter pylori (H. pylori) infection. A 64-year-old man was referred to our hospital for the treatment of early gastric carcinoma. He underwent distal gastrectomy with regional lymph node dissection. In the operation, several small nodules were recognized at the surface of the liver, and one of these hepatic nodules was resected as biopsy. The hepatic lesion exhibited a nodular growth pattern consisting of centrocyte-like cells and intermediate lymphocytes, which were stained with CD20 and CD79a, but not with CD43 or CD45RO. The neoplastic cells form lymphoepithelial lesions infiltrating bile ducts. From these findings the liver lesion was diagnosed as marginal zone B-cell lymphoma of MALT type. Histological examinations of resected stomach and residual stomach showed H. pylori infection. There is a strong association between the presence of H. pylori in the stomach and in the bile, and therefore, the H. pylori may be related to the etiology of primary hepatic MALT type lymphoma.