<s>[INST] I am a 32 year old female and have a Small pencil eraser sized knot on my left sternum below my breast, it is very tender and moveable. I ve noticed it for about one month. I have also noticed that the left side of my sternum is much more prominent than the right in the same area. I haven t had an recent surgery or injury. I have also had a negative mammogram two months ago. Is this something I should be concerned about? [/INST] Hi! Good evening. I am Chat Doctor answering your query. Your problem requires a physical examination before opining on it. If I were your doctor, after a physical examination of the lump, I would advise you for an FNAC or an excision biopsy if fully mobile and free from any attachment. Further management would depend on the report of the FNAC. Till then, you could go for an anti-inflammatory and a proton pump inhibitor for a symptomatic relief. I hope this information would help you in discussing with your family physician/treating doctor in further management of your problem. Please do not hesitate to ask in case of any further doubts. Thanks for choosing Chat Doctor to clear doubts on your health problems. I wish you an early recovery. Chat Doctor. </s>