Lipoma underarm for 13 yrs that gets painful each time i get premenstrual symptoms. Should I be worried? (photo)

The mass may represent breast tissue that is responsive to perimenopausal hormones. Best, Dr. KaramanoukianLos Angeles

Thank you for sharing your question and photograph.  If this mass is indeed a lipoma a small surgical procedure can be done to remove it in its entirety without further issues with pain or growth.  That said, based on its location and your premenstrual symptoms I would rather have you see your ob/gyn for an in-person evaluation.  It seems more likely that this mass is accessory breast tissue and should be appropriately evaluated before surgical removal.  Hope this helps. 

Although you may have a lipoma under your arm, lipomas do not change size or respond to menstrual cycles. More likely you have ectopic breast tissue (breast tissue slightly beyond the usual boundary of the breast) that becomes more tender or larger with hormone changes. This is not harmful, but if it is bothersome to you either because it hurts or because prevents you from wearing sleeveless clothes, see a doctor and discuss removal of the tissue through a cosmetically favorable armpit incision or liposuction.