Acromioclavicular Joint Cyst

Acromioclavicular Joint Cyst
Supraspinatus tear with geyser sign. TVF, thick viscous fluid; S, septa; FC, fibrous capsule; ACJ, acromioclavicular joint.
  • Acromioclavicular joint cyst is a rare abnormality, secondary to a chronic tear in the rotator cuff.
  • A fibrous capsule envelops the cyst. Similarly, the cyst is composed of thick and viscous fluid.
  • Moreover, the fluid erupting from the AC joint is known as “geyser sign”.

This article describes a case of geyser sign with acromioclavicular (AC) joint cyst with underlying rotator cuff tear in a 91-year-old male cricket team coach. The patient presented to the emergency with complaints of right-sided shoulder and neck pain.

The patient’s physical examination showed a lump on his right shoulder, above the AC joint. The lump had a year’s history and continued to enlarge since then. However, he did not complain of any pain. The lump was painless, firm, non-mobile and non-tender. He complained of difficulty raising his right arm with restricted shoulder movement. Similarly, he was also unable to lie down on his right side because of the pain. His medical history was unremarkable and did not reveal fever, weight loss or any other symptoms. Neither did he have any previous surgeries of the affected shoulder.

Ultrasound examination revealed a cystic lesion.

The ultrasound revealed that the lump was a cystic lesion located above the AC joint, measuring 8.0 × 4.5 × 2.1 cm. The findings were further suggestive of a full thickness chronic ST tear, associated with degenerative changes, also. Real time ultrasound examination further showed synovial fluid escaping from the rotator cuff, decompressing superiorly through the AC joint and across the subacromial bursa (geyser sign). In addition, the long head of the biceptal groove appearing hypoechoic was suggestive of element tendenopathy.

Doctors performed an MRI to confirm the diagnosis of acromioclavicular joint cyst . MRI showed a full-thickness tear in the posterior part of the ST. The lesion was cystic with peripheral enhancement.


Sonographic Presentation of the Geyser Sign

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Dr. Aiman Shahab is a dentist with a bachelor’s degree from Dow University of Health Sciences. She is an experienced freelance writer with a demonstrated history of working in the health industry. Skilled in general dentistry, she is currently working as an associate dentist at a private dental clinic in Karachi, freelance content writer and as a part time science instructor with Little Medical School. She has also been an ambassador for PDC in the past from the year 2016 – 2018, and her responsibilities included acting as a representative and volunteer for PDC with an intention to make the dental community of Pakistan more connected and to work for benefiting the underprivileged. When she’s not working, you’ll either find her reading or aimlessly walking around for the sake of exploring. Her future plans include getting a master’s degree in maxillofacial and oral surgery, settled in a metropolitan city of North America.


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