A nonsurgical treatment was recently reported. The patient was a 33-year-old male with a cyst like the one you describe and mild rotator cuff tendinitis. Instead of opening the shoulder or doing arthroscopy, the doctors aspirated or "deflated" the cyst using suction. While the shoulder was numb from anesthesia, the doctors used ultrasound to find the cyst. They then inserted a large needle that sucked the contents out.

Within six months of the procedure, the patient regained full shoulder strength. He had pain relief in overhead shoulder activities, such as playing tennis. Up to a year after the procedure, the cyst had not come back.

This procedure seems to be an effective, minimally invasive treatment for patients who don't want to have surgery for cysts compressing the nerve over the shoulder blade. Ask your doctor whether this treatment is an option in your case.