I just discovered a lump on my right collarbone (mid-clavicle). The bone feels smooth along the top, but there is a pronounced lump coming from underneath it and seeming to wrap around. It is very hard, but difficult to tell whether it is bone or firm tissue. I have no idea how long it has been there. I am a 28 year old female with no history of trauma, and I have no other symptoms. I am mildly obese with large breasts, if that is relevant- maybe a fat deposit? (although it seems a bit too firm for that). I won t have insurance for another 3 weeks, and I am concerned.