I can understand your concerns,a bursa is a fluid filled sac which acts a cushion between tow hard surfaces to avoid friction,they can be find between bones,joints,tendons and muscles.
means inflammation of these bursae due to injury
,infection or repetitive movements of the area such as in labourers,Manual workers,weight lifters and sportsmen depending upon the area of the body they are using.
Now the point is the main concerns arises when it's inflamed when it gives you a lot of pain and restrictions in movement sometimes. But you said that its not painful but the size of it is quite large according to you.
So if its not symptomatic then I can suggest any treatment,because the problems arise when it is inflamed as I said earlier.
So I think you need to see a dermatologist
again to rule out other soft tissues growth like a Lipoma
I think this answer will be of help.
Thanks very much.