I have cyst on my shoulder? what's the treatment?

Depends: There are lots of things that can look like a cyst on your shoulder. These include actual cysts of various kinds, certain osteopathic findings (specifically herniated trigger points), muscle strains/pulls, swollen lymph nodes, tumors and other masses, abscesses, etc. Each of these has its own treatment. You need to get it looked at and diagnosed, then you can get it properly treated.

Depends: If you have a cyst beneath the skin near the shoulder then observation vs surgery needs to be entertained. If the cyst is deep and was seen on MRI within the shoulder joint or near the shoulder joint and its symptomatic then surgery may be needed but it must be properly evaluated by an orthopedic surgeon first.