Ganglion cyst. Ganglion cysts can occur due to irritation of a tendon that is overused or irritated. Most commonly, they occur in the wrist. These cysts can be painful, and over time, can irritate the tendons they overlie. Dr.Marcus is using Ultrasound Guidance to drain the cyst and then inject cortisone (an anti-inflammatory medication) in order to prevent the cyst from returning. This procedure is done in the office, and is much simpler than having the cyst surgically removed. Share with someo