What causes lump under the armpit during puberty stage?
Patient: My 12 year old son is in puberty.  He has quite a bit of pubic hair, under arm hair, acne and one nipple has enlarged and a lump behind it.  His penis had enlarged quite a bit and testicles.  However, over the past 6 weeks or so he has noticed about 1/2" in diameter hard lump under his left under arm.  In the beginning it hurt, but said it doesn't now.  The size has not gone down.  I also feel another lump in the other underarm as well.  Not as big though.  Is this something we should be concerned about? Doctor: Hello,  It could be a lymph node. It indicates an infection in the nearby region. If lump persists you can consult a general surgeon and plan for an ultrasound scan.  Hope I have answered your query. Let me know if I can assist you further.  Take care  Regards, Dr Shinas Hussain, General & Family Physician