Primary low-grade B-cell lymphoma of MALT-type occurring in the liver: a study of two cases

Primary non-Hodgkin's lymphomas of the liver are rare. One specific clinico-pathological entity has been identified as hepatosplenic gamma/delta T-cell lymphoma. Recently, another distinct primary lymphoma of the liver has been recognised as primary low-grade hepatic B-cell lymphoma of mucosa-associated lymphoid tissue (MALT), based on a study comprising four cases. We analysed two additional cases of this particular non-Hodgkin's lymphoma, not only by morphology and phenotyping, but also by genotyping and cytogenetic analysis.

This type of non-Hodgkin's lymphoma is characterised by a dense lymphoid infiltrate, localised in the portal tracts, and is associated with lympho-epithelial lesions of the bile ducts, thereby mimicking hepatitis or an inflammatory bile duct disorder. In one of our cases, translocation t(3;14)(q27;q32) was identified as the sole cytogenetic abnormality. A high incidence of trisomy 3 has been associated with marginal zone B-cell lymphomas, and fluorescence in situ hybridisation as well as comparative genomic hybridisation studies have shown frequent involvement of the long arm of chromosome 3. Nevertheless, t(3;14)(q27;q32) involving BCL6 gene, located at 3q27, has not yet been found.

Our findings suggest a role for the BCL6 gene in the histogenesis of this particular lymphoma.