Lipoma arborescens associated with osseous/chondroid differentiation in subdeltoid bursa
A 43-year-old, right-handed woman presented with complaints of pain and discomfort in her right shoulder. She had no history of previous injury or minor problems with her shoulder. The symptoms had begun after labor related to institutional food service for 1½ years. She had occasionally experienced a catching sensation and aggravated pain in the shoulder with labor activity. Symptoms were not alleviated by rest or non-steroidal anti-inflammatory drugs. Physical examination revealed positive findings for Neer's sign and Hawkins impingement test, Speed test and O’Brien's test. Patient's rotator cuff muscle strength was normal and no musculature atrophy was observed. The active range of motion (ROM) of the shoulder joint was mildly restricted during flexion, abduction and internal rotation, but passive ROM showed full range. The laboratory investigations including erythrocyte sedimentation rate and serology showed no significant results. Plain radiograph of shoulder demonstrated multiple rounds and ring like calcifications at the right glenohumeral joint with entheophyte at greater tuberosity of right humeral head []. Magnetic resonance imaging (MRI) of the shoulder showed a fluid-filled paralabral ganglion cyst that originated at the posterior superior labrum, forming a large cystic mass located at suprascapular and spinolgenoid notch around the spine of scapula [Figure and ]. The cyst originated at a tear of the superior labrum and extended to the posterior aspect of biceps long head origin [Figure and ]. The axial MRI also revealed fatty mass, which showed iso-signal intensity to the subcutaneous fat on all sequences, under intermuscular space located between anterolateral cortex of the humeral head and anterior belly of the deltoid muscle []. Another encapsulated mass was found in intermuscular space between infraspinatus and the deltoid muscle []. Abundant villous projection on the medial portion of the mass was located with multiple rings like or round low intensities on all pulse sequences. It showed background low signal intensity on T1-weighted image and high signal intensity on T2-weighted image, representing calcification arising from chondroid matrix [Figure and ]. Arthroscopy revealed a type II SLAP lesion with mild synovitis, but the articular cartilage of the humeral head and glenoid was intact. The detached posterior-superior labrum was fixed with sutures by insertion of two metal anchors. Patient subsequently underwent a separate incision laterally around the acromion and medially along the lateral one-third of the spine of the scapula. The origin of the deltoid was detached from the acromion and from the exposed part of the spine of the scapula. We retrieved LA and lipoma respectively. Lipoma size was 1.8 cm × 2.2 cm × 1.7 cm. LA size was 7.1 cm × 2.8 cm × 2.6 cm in the form of encapsulated mass. Opening the capsule revealed villous projection of fatty synovial tissue associated with central large whitish cartilaginous nodules attached to villous synovium []. Histologic examination demonstrated that diffuse papillary proliferation of the synovium with near total replacement of subsynovial tissue into mature fat tissue. Extensive area of osteochondral metaplasia in villous fat tissue was also seen [Figures and ].\nPost-operatively, the arm was placed at the side in a sling for 3 weeks. Passive motion including external rotation of the shoulder and ROM of the elbow were started immediately. This was followed by a home-based rehabilitation program of progressive ROM. Strengthening exercises for the rotator cuff, scapular stabilizers and deltoid were started 6 weeks post-operatively. She achieved full recovery in her affected shoulder within 3 months of surgery. At 2-month follow-up, the ultrasonogram demonstrated complete removal of LA, lipoma and cyst. She was asymptomatic and showed no recurrence of calcification on plain radiographs at a final follow-up 3 years after surgery.