I have a lump under my arm, which only comes up the week before my period and is quite sore for a week but then goes away after my period. I’ve had it for a few years now and it hasn’t changed at all. Should I be worried?
Anonymous

Any lump near the breast or under the arm should be checked by a doctor. There's no need to be worried because the most likely reason is something simple and harmless such as breast tissue swelling up before a period. Breast tissue extends up into the armpit and can be influenced by the hormones of the menstrual cycle. Some women will notice lumps or tenderness in the breast just before a period that will go away again during a period, just as you've noticed. Swollen lymph glands can also appear as lumps under the arm as can other uncommon conditions. Without seeing the lump it's impossible to know what it is, so visit your doctor for a proper diagnosis.