Nodal marginal zone lymphoma resembles what is seen in either the splenic type or MALT lymphoma when it metastasises to lymph nodes, but without the extranodal disease. It is sometimes known as Monocytoid B-cell lymphoma. It comprises less than 2% of B cell lymphomas. Although the median age of presentation is about 60, it can occur in children. In about 20-25% of cases, Hepatitis C can be detected. It affects peripheral lymph nodes and very rarely bone marrow and peripheral blood.
The tumor usually surrounds a reactive follicle and expands into the interfollicular areas. The tumor cells are heterogeneous and are made up of the same sorts of cells seen in MALT lymphomas. The immunophenotype is non-specific and the only common chromosomal abnormalities are trisomies of 3, 7 and 18. The extranodal type translocations are not seen.
The tumor is usually indolent though transformation to a large B-cell lymphoma may occur.
A pediatric form is described. It occurs predominantly in boys (9:1), mainly in head and neck lymph nodes. This tumor is still very indolent and does not require aggressive systemic chemotherapy