A form of non-Hodgkin's lymphoma characterized by an abnormal proliferation of B-lymphocytes. It is a cancer of the B-lymphocytes (a type of white blood cell) which, if untreated, can spread to other parts of the body such as the bones and the liver. It differs from diffuse large B-cell lymphoma in that it is a low-grade lymphoma that usually develops slowly. Follicular lymphoma often transforms into diffuse large B-cell lymphoma. See also Follicular lymphoma