Age / Sex : 75 / M

Chief complaint : A bulging soft tissue mass in right shoulder area

What is your diagnosis?

Two weeks later, you can see the final diagonosis with a brief discussion of this case (Please submit only one answer).

Courtesy : 이민희 (Lee Min Hee), 울산의대 서울아산병원 (Asan Medical Center, University of Ulsan College of Medicine)

Acromioclavicular joint cyst (AC joint cyst) - Geyser sign

Discussion

Findings

1.A bulging-out soft tissue mass-like lesion in right shoulder on plain radiographs

2.Massive, full thickness rotator cuff tear

3. A multilobulating cystic mass is located in the superior aspect of AC joint. Its internal fluid is communicated with the fluid in glenohumeral joint, through the torn rotator cuff, subacromial bursa, and AC joint space.

1.Tshering Vogel DW, Stienbach LS, Hertel R, Bernhard J, Stauffer E, Anderson SE. Acromioclavicular joint cyst: nine cases of a pseudotumor of the shoulder. Skeletal Radiol 2005; 34:260-265

2.Hiller AD, Miller JA, Zeller JL. Acromioclavicular joint cyst formation. Clinical Anatomy 2010; 23:145-152