Leukosis is a term used to describe a group of cancers that affect the immune system cells. These cancers are also referred to as lymphomas or lymphatic tumors and can develop in different parts of the body, including the lymph nodes, spleen, liver, and bone marrow. Other synonyms commonly used include lymphatic cancer, lymphadenoma, lymphosarcoma, and malignant lymphoma. Leukosis is a serious condition that requires prompt diagnosis and treatment. Symptoms may include weight loss, fatigue, fever, night sweats, and swollen lymph nodes. Treatment options may include chemotherapy, radiation therapy, and bone marrow transplantation, depending on the type and stage of the cancer.