The definite cause of Non-Hodgkin's Lymphoma is unknown but it has been linked to some viruses and toxins as benzene and pesticides. Now let's talk About a general simplified view of the mechanism of this cancer. This cancer causes production of lots of abnormal lymphocytes. A normal lymphocyte has a life span but the abnormal one doesn't. These lymphocytes continue to grow and divide until they cause crowding of the lymph nodes. As a result, lymph nodes get enlarged.