How Many Lymph Nodes Do You Have Under Your Arm?

Axillary lymph nodes are commonly involved in breast cancer because of their proximity to breast tissue. Involvement of the lymph nodes makes it more likely that cancer spreads to other locations. Lymph node swelling is common. Non-cancer reasons for swelling can include injury, infection, colds and viral infections, such as measles, mumps or mononucleosis. Side effects from medications, such as phenytoin, can also cause swelling.