Hi, The axillary lymph nodes drain lymphatic fluid from the chest wall, and in some cases the lungs. There are two thoughts here, either the lump is from an enlarged lymph node, in that case, the exact source of where the infection is coming from needs determined or it is an abscess or folliculitis in the axilla itself causing the lump. Either one is possibility here. Regardless of the exact source, this needs looked into and likely antibiotics started, I think he needs evaluated sooner rather than later here, potentially even bloodwork may be needed. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. David Girardi, Internal Medicine Specialist