I Have A Very Small Lump Near The Armpit Of

I have a very small lump near the armpit of my left arm that is painful to the touch but not bothersome unless it is palpated. Mammograms and ultrasounds(with color) says it is nothing more than a swollen lymph node. But I have had fatty lipomas in the past in various areas of my body but they have not been painful to touch, squeeze or palpate.