Tailbone cyst may be caused by trauma, obstruction of blood vessels in the bone, local soft tissue swelling and other factors. 1. Trauma: Bone damage caused by trauma to the tailbone may lead to the reduction of bone cells, thus affecting bone resorption, abnormal bone metabolism, and increased accumulation of materials, inducing tailbone cysts. 2. Intraosseous blood vessel obstruction: prolonged extrusion and other internal and external factors may lead to intraosseous blood vessel endings obstruction, blood can’t flow smoothly, stagnation occurs, affecting bone resorption, which may also lead to caudal cysts. 3. Local soft tissue swelling: the outer soft tissue around the tailbone is thin, if there is malnutrition of the soft tissue or insufficient blood supply, etc., local swelling will be formed. Although it occurs in the soft tissue, due to the small physiological curvature of the tailbone, it can also appear localized obvious cysts. There is a clear relationship between bone cysts and bone metabolism; patients often experience increased bone destruction and decreased bone synthesis, which results in impaired bone metabolism and the formation of bone cysts. Patients who find tailbone cysts should actively cooperate with doctors and clarify the treatment plan for active treatment to avoid delaying the condition.