Hello. For a while I have had a lump on my elbow that when squeezed a white substance comes out. It usually does not hurt, and once I am able to get all of its content out, it takes months before I have to squeeze it again. In the past month, though, two new lumps have appeared. These do not secrete any substance when squeezed, and they look dark in color when my elbow is bent. The are not painful, but have continued to grow. Should I be concerned about them?