I Was Told That I Have A 'ganglion Cyst' On

I was told that I have a 'ganglion cyst' on my AC joint of my collarbone .. what is weird is that I have noticeable degenerative changes to the shoulder bone on the same side. My other should is not showing this. I have had: x-ray, u/s and CT of the area. All confirm no vascuslar association. What are your thoughts?..I was told to wait 6 months ( or if anything else changes ( size, increased discomfort etc.) to do another CT..