Lymph nodes are small swellings of lymphatic system which is part of immune system. There can be 2 types of lymph node cancer. Firstly lymph node cancer or lymphoma and secondly lymph node cancer as secondary after metastasis from other area. Its symptoms include unexplained fever, fatigue, night sweats and weight loss. If the lymph node glands are deep in the abdomen, the cancer in these glands causes pressure on other parts resulting in pain in low back. For differential diagnosis, go for MRI and different tests.