Often a bursitis is associated with an underlying tendinopathy or enthesopathy and it represents the inflammatory response of the synovial entheseal complex but this is not always the case.
We often see isolated bursopathy in younger patients doing repetitive work or sport in shoulders where the tendons look pristine.
Post traumatic bursitis is another entity where bursopathy exists without tendinopathy.
Rheumatoid patients also like to develop isolated bursopathy as the synovium becomes inflamed.
So when I see a bursopathy I always look hard for an underlying tendinosis or enthesopathy process, but on some occasions it is not present.