What is NHL follicular lymphoma?

Most carry t(14;18), juxtaposed BCL-2 gene w/Ig heavy chain gene, this causes unregulated expression of BCL-2 an inhibitor of apoptosis and thus increased survival of germinal centers leading to lymphoma. So we have replacement of lymph nodes with enlarged follicles consisting of small cleaved lymphocytes Most common NHL, presents middle age, fairly indolent survival 8 years but not amenable to chemo, 30-50% transform to more aggressive large B-cell lymphomas [not richter syndrome]