Hi, I have a visible pea-sized, hard, lump under my skin on my right kneecap. I think it has developed slowly. I don t remember when it began, but I think I first noticed something about six years ago. It is now become a nuisance. My question is, Should I be concerned about this and have it checked out further? More info: The lump is painful when I touch it, and very painful when I press on it. When I exercise, such as riding a bike or doing an aerobic activity such as Zumba, my right knee will hurt afterwards. It will be very painful to go downstairs, for example. By the next day, the pain will be gone, though it does still feel sensitive. Even though I have had this for a few years now, the pain has increased over the last year. I am not overweight. I don t recall any specific injury. I have exercised moderately, but regularly over the years.