What causes lump in the breast and underarm?
Patient: I have my period and about a week ago I felt a small lump in my underarm, it hurt for a  few days then went away.  Today I noticed it again it´s a lot smaller.  Also every month a week before I start my period I get a lump in my brest which is apparently a sist but it´s benign, after my period it disappears. Doctor: HI. undergone through the classical nice history you have given.This is a classical finding in a condition called '' fibroadenosis''. This is a group of benign lesions.These are hormone dependent.So they grow and pain and reduce as per your cycle.Nothing much to worry except for the discomfort they do.Yet to confirm -go for an FNAC- fine needle aspiration cytology. You can get rid of it if it is small by a small surgery; the problem goes away and one gets tissue diagnosis.