Overview
Bursitis is inflammation of a bursa (a tiny, fluid-filled sac that functions as a gliding surface to reduce friction between tissues of the body). When injury or inflammation of a bursa around the shoulder joint occurs, shoulder bursitis is present.
Cause
Injury
Infection (rare)
Rheumatic condition
Symptoms
Localized pain or swelling
Tenderness
Pain with motion of the tissues in the affected area
Diagnosis
Physical examination and medical history consultation
X-ray
MRI
Treatment
Application of ice
Rest
Non-steroidal anti-inflammatory medications
Aspiration (removal) of the busa fluid
Cortisone injections
Physical therapy
Antibiotic therapy (if caused by infection)
Surgical drainage
Source: http://www.medicinenet.com/shoulder_bursitis/article.htm