Hi, Brief answer: It is likely that the lump is a swollen, tender lymph node due to an inflammatory reaction to infection, not cancer. This is called reactive lymphadenopathy. Detailed answer: An enlarged lymph node (lymphadenopathy) can be caused by inflammation due to an infection or may be caused by cancer. Lymph nodes that are tender, rubbery, and can be moved around freely are rarely cancer. Tender and painful enlarged lymph nodes are likely caused by an inflammatory reaction to a viral infection like the flu and this is called lymphadenitis. Humira and other biologic drugs, which act by suppressing the body’s immune system, may increase the risk of cancer of the lymph nodes (lymphoma). But lymphoma is still very rare, even in patients taking biological drugs. It is far more likely that an enlarged lymph node is reactive lymphadenopathy causing lymphadenitis. Reactive lymph nodes will typically resolve on their own within a few weeks or sooner. Applying a warm compress can help with swelling and taking over-the-counter pain relievers such as ibuprofen or acetaminophen can help with the pain and soreness. It is best for you and your son to talk with his doctor to see if any evaluation or testing including bloodwork or imaging is needed. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Aaron Shapiro, General & Family Physician