Inferior paralabral ganglion cyst of the shoulder with labral tear -- a rare cause of shoulder pain.

INTRODUCTION: Paralabral ganglion cysts of the shoulder are rare, and their pathogenesis is similar to that of meniscal cysts. The paralabral cysts are most frequently reported along the posterior, superior, and anterior aspects of the glenohumeral joint and are uncommon inferiorly to the joint. These cysts rarely become evident clinically, unless they cause compression of surrounding structures, i.e. nerve.

PATIENTS AND METHODS: We report a retrospective series of five patients with inferior paralabral ganglion cysts of the shoulder without compression of the surrounding nerve which were treated during the period from March 2007 to December 2009. All these patients presented with only chronic shoulder pain as their chief complaint, and preoperative MRI showed the cyst over the inferior aspect of a torn glenoid labrum. All patients were treated by arthroscopic cystic decompression with labrum repair. All patients were re-evaluated with MRI performed at an average of 15 months postoperatively. The clinical outcome, including the Constant score, was assessed for all patients at a median of 16 months postoperatively.

RESULTS: All the five patients had remission of pain and were satisfied with the shoulder function. The postoperative MRI in all patients showed no labral cyst recurrence. The median Constant score improved from a preoperative level of 81.5 points to 98.0 points at last follow-up.

CONCLUSION: This study demonstrates that, in the absence of any nerve compression symptoms around the shoulder joint, inferior paralabral cysts with labral tear also be considered in the differential diagnosis of chronic shoulder pain. Arthroscopic repair of the cyst with repair of the labrum can lead to the disappearance of symptoms. Knowledge of this clinical condition and its imaging features is critical for a correct diagnosis of this uncommon cause of chronic shoulder pain.

LEVEL OF EVIDENCE: Level IV. Retrospective therapeutic study.