Age / Sex : 76 / M

Chief complaint: Palpable mass above the acromioclavicular joint area

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

Courtesy of Sun Ki Kim, Incheon St. Mary's Hospital, The Catholic University of Korea

Discussion

Answer:  

Geyser sign (Acromioclavicular joint cyst)

Findings:

MRI  :

1. Large cyst formation above the AC joint


2. Full thickness tear of supraspinatus and infraspinatus tendons.

Differential Diagnosis:

epidermoid cyst, aneurysm, tumor, infection

Diagnosis: 

Geyser sign (Acromioclavicular joint cyst)

Discussion:

Geyser sign   

-  a large fluid filled cystic mass above the AC joint, combined with a full thickness rotator cuff tear.

-  communication between glenohumeral joint and the acromioclavicular joint.

-  glenohumeral joint fluid "erupts" superiorly through the degenerative AC joint

References:

1. Cooper HJ, Mililo R, Klein DA, DiFelice GS. The MRI geyser sign: acromioclavicular joint cysts in the setting of a chronic rotator cuff tear. Am J Orthop 2011;40:E118–E121


2. Mohana-Borges AV, Chung CB, Resnick D. MR imaging and MR arthrography of the postoperative shoulder: spectrum of normal and abnormal findings. Radiographics. 2004;24(1):69-85.


3. Mullett H, Benson R, Levy O. Arthroscopic treatment of a massive acromioclavicular joint cyst. Arthroscopy. 2007 Apr;23(4):446.e1-4.