Association of intramuscular cysts of the rotator cuff with tears of the rotator cuff: magnetic resonance imaging findings and clinical significance.

Cystic lesions that arise adjacent to the shoulder have been reported in association with labral tears or as an unusual manifestation of massive rotator cuff tears. The purpose of this study was to define the relationship between intramuscular cysts of the rotator cuff and tears of the rotator cuff. Thirteen cases of intramuscular cysts of the rotator cuff were identified on magnetic resonance imaging of the shoulder and analyzed retrospectively along with the clinical data. Surgical findings were retrospectively reviewed in 5 patients who underwent follow-up arthroscopy. This series shows that intramuscular cysts of the rotator cuff are associated with small, full-thickness tears or partial undersurface tears of the rotator cuff. These cysts are easily identified on T2-weighted sequences and, when present, should always prompt a thorough search for associated rotator cuff pathology.