Primary low-grade hepatic B-cell lymphoma of mucosa-associated lymphoid tissue (MALT)-type.

We describe the clinical, histological, and immunohistochemical features of four cases of primary low-grade B-cell lymphoma of the liver. The lymphomas were first seen as a solitary nodule in two patients and as two nodules in the third patient. These were found incidentally in an otherwise normal liver during abdominal surgery for other causes. In the fourth patient, several up to 2 cm nodules of lymphoma were found in a liver removed before transplant for chronic active hepatitis and cirrhosis. There was no evidence of lymphoma elsewhere in any of the patients. One patient has remained well, without evidence of lymphoma, 1 year after resection, one died intraoperatively, one is lost to follow-up, and the transplanted patient died 1 year after transplant from complications without evidence of recurrent lymphoma. The histology was typical of low-grade B-cell lymphoma of mucosa-associated lymphoid tissue (MALT)-type with centrocyte-like cells surrounding reactive B-cell follicles and forming lymphoepithelial lesions with bile ducts. Primary hepatic lymphomas are rare, and most reported cases have been high-grade B-cell lesions. The liver should be added to the list of extranodal sites where low-grade MALT lymphoma may occur.