Cysts within and adjacent to the lesser tuberosity and their association with rotator cuff abnormalities.

OBJECTIVE The purpose of our study was to determine the incidence of cysts in and adjacent to the lesser tuberosity and their association with rotator cuff abnormalities and subcoracoid impingement. MATERIALS AND METHODS A retrospective review of 1,000 consecutive MRI examinations of the shoulder was performed by consensus of two radiologists. Cysts were grouped by location into one of two groups: those within the lesser tuberosity and those adjacent to the lesser tuberosity. The rotator cuff was defined as intact, partial tear or tendinosis, or full-thickness tear. The shortest distance from the coracoid to the humeral head was measured on axial images. RESULTS Forty-eight patients (26 women, 22 men; age range, 35-79 years; mean age, 61 years) had cysts adjacent to or within the lesser tuberosity. Thirty-two patients (67%) had cysts just superior to the tuberosity and 16 (33%) had cysts in the lesser tuberosity, resulting in an incidence of 3.2% and 1.6%, respectively. All 16 patients (100%) with lesser tuberosity cysts had subscapularis and supraspinatus tendon abnormalities including 11 (69%) full-thickness supraspinatus tears. Patients with cysts superior to the tuberosity had 20 (63%, p = 0.004) abnormal subscapularis tendons and 28 (88%) abnormal supraspinatus tendons, including six (19%) full-thickness tears (p = 0.002). The coracohumeral distance was noted to be less than 10 mm in 10 patients (63%) with lesser tuberosity cysts as compared with 10 patients (31%, p = 0.06) with cysts superior to the tuberosity. CONCLUSION Cysts located within the lesser tuberosity are rare and are indicative of subscapularis and supraspinatus tendon abnormalities.