A myxoid cyst (also known as a synovial cyst or mucous cyst) is a ganglion (tissue mass) of the adjacent joint, caused by leakage of fluid from the joint into the surrounding tissue. These cysts often appear clinically with osteoarthritic symptoms and are a red or bluish colour, producing a gelatinous material if punctured.
The cyst can be linked to the joint by injection of methylene blue; however, more recently, surgical techniques have been developed. Common treatments consist of injection of corticosteroids, repeated puncture and drainage of the cyst or surgical excision. Total immobilization may lead to fixation of the joint and is not advised.