Illustration of a human monoclonal antibody drug (blue and orange) and non-Hodgkins lymphoma cells (dark purple). Lymphoma is a malignant (cancerous) growth of white blood cells (lymphocytes). White blood cells are part of the bodys immune system and circulate in a clear liquid called lymph. There are many types of lymphoma depending on the cells affected. All lymphomas however, are divided into 2 types, Hodgkins lymphoma and non-Hodgkins lymphomas. Hodgkins lymphoma is characterised by the presence of Reed-Sternburg cells, a giant type of macrophage. All other lymphomas are non-Hodgkins. The cause of lymphomas are not known.