Intra-vs. extra-articular fluid collection. Evaluate fluid collection seen on CT in subscapularis. There is a collection anterior to the subscapularis muscle with intermediate T1 signal, high T2 signal, and rim enhancement with central low signal on post-contrast imaging which is compatible with an infected fluid collection. This collection tracts along the subscapularis muscle to its insertion on the humeral head and communicates with the subdeltoid bursa. The collection measures at least 1.5 cm in depth and 4.5 cm in the transverse dimension, however, a portion of the collection is not included in the field of view. Additionally, there is a large joint effusion.Bone marrow signal is within normal limits.Mild osteoarthritis affects the acromioclavicular joint. Glenohumeral joint alignment is within normal limits. Glenohumeral joint articular cartilage is intact. There are subchondral cysts within the humeral head which are likely degenerative. No rotator cuff tear is identified.
Extra-articular infected fluid collection anterior to the subscapularis muscle is likely in the subcoracoid bursa with extension into the subacromial/subdeltoid bursa. 