The architectural pattern of the proliferating process, that of either a diffuse or a follicular appearance, is of prognostic value - follicular MLs have a better prognosis than diffuse MLs and are rare below the age of 20. The follicular structure implies B cell immunologic lineage . Follicular lymphomas must be carefully distinguished from reactive follicular hyperplasia. Phenotype Certain lymphomas, such as marginal zone B cell MLs, tend to grow filling lymph node sinuses. There are prognostic and some treatment differences between T and B cell processes.
Immunochemistry allows for phenotypic determination of cell lineage.
Reactive lymphoid populations are polyclonal . Genotype In T cell lymphomas and in some B cell lymphomas clonality cannot be determined by phenotyping. Molecular genetic studies, in particular analysis, can detect clonality by probes to immunoglobulin and T cell receptor genes. Thus, both lineage and clonality can be identified. Chromosomal translocations have been associated with specific types of lymphoma.