Hello, aberrant breast tissue that can occur well up here in the armpit area, actually disconnected from the tail of the breast, or there can be an extension of the normal tissue of the tail of the breast well up into the armpit area. If you see developmental stage stage of breast it is not unusual to see breast tissue in armpit. Well the problem is, it is common that due to hormonal stimulus during pregnancy this aberrant breast tissue Will grow more along with normal breast tissue and become more prominent and may irritates you more. So it is better to get it removed before you planning for pregnancy. if it is associated with an accessory nipple, then removing that accessory ripple and areola along with some of the underlying breast tissue, can be helpful both functionally and cosmetically.