There are many reasons for the sudden growth of a bag on the neck, generally divided into the following: first, it may be a boil caused by inflammation of the lymph nodes. Secondly, it may be caused by leukemia. Patients with leukemia may also have bleeding, anemia, infection and enlarged liver and spleen. Third, it may be caused by some other tumor diseases that cause cancer cells to metastasize to the neck, resulting in a bag on the neck, such swollen lymph nodes are generally characterized by an unsmooth surface and hard texture. Fourthly, Hodgkin’s lymphoma and non-Hodgkin’s lymphoma caused by viral infection may also lead to swollen lymph nodes. Fifth, it is more common to see swollen lymph nodes in the neck caused by thyroid disease, and generally hyperthyroidism can cause swollen neck. No matter what the situation and cause of a bag on the neck need to pay attention to, promptly go to the hospital, clear cause and then choose the appropriate method of treatment to avoid delaying the disease.