Lymphoma. Coloured lymphangiogram X-ray of growths (white) in a child's iliac (pelvic) lymph glands. Lymphoma is a malignant (cancerous) growth of white blood cells (lymphocytes). There are many types of lymphoma depending on the cells affected. All lymphomas however, are divided into two types, Hodgkin's lymphoma and non-Hodgkin's lymphomas. Hodgkin's lymphoma is characterised by the presence of Reed- Sternberg cells, a giant type of macrophage. All other lymphomas are non-Hodgkin's. The cause of lymphomas is not known. Treatment is with radiation therapy and chemotherapy.