There is a painful bump on the bone of the caudal vertebrae. After ruling out that it is a fracture caused by trauma, it is more likely to be considered a sacral canal cyst, or a disease such as intra-sacral canal tumor, vertebral spinal membrane bulge, or latent hair sinus. It is recommended to go to the local hospital and ask experienced clinicians to help further clarify the diagnosis and guide the treatment.1.Sacral cysts: most sacral cysts are congenital, with slow growth rate and long history, and patients often have no obvious discomfort symptoms at the beginning of the disease. Only when the sacral canal cyst increases in size to a certain extent and gradually begins to invade and compress the motor and sensory nerves innervating the saddle area and perineum in the sacral canal, patients will experience obvious pain in the lumbar region and sacrococcygeal region, i.e., a bump on the bone of the caudal vertebrae is very painful, as well as pain and discomfort in the perineum. Some patients also present with a localized bump, positive tenderness, and radiating pain at the root of the thigh, similar to sciatica, and progression of the disease may even affect the patient’s motor function and lead to neurogenic claudication. When patients have obvious clinical symptoms, surgical treatment is recommended to remove the sacral canal cyst, and attention should be paid to the complete removal of the cyst envelope during the operation to avoid recurrence; 2. Tumor in sacral canal: clinically, it is mostly seen as a solid tumor, which often manifests as a local abnormal mass and gradually bulges, i.e. it manifests as a painful bump on the bone of the tailbone. When the volume increases, it will invade and compress the peripheral nerve roots, leading to motor and sensory dysfunction in the saddle area and perineum, and the clinical performance is similar to that of sacral canal cyst. It is mainly identified by MRI examination of sacrococcygeal spine. MRI enhancement scan can reveal significant enhancement of tumor in sacral canal. It is recommended to remove the tumor completely in early surgery, and a small amount of tumor tissue should be retained for pathological examination after surgery, and whether radiotherapy or chemotherapy is needed in the later stage should be decided according to the examination results; 3. Intraspinal spinal cord bulge: congenital spina bifida is complicated by spinal membrane and/or spinal cord bulge, and MRI examination of vertebral body can help to identify it. Treatment is mainly based on the patient’s symptoms, for no obvious symptoms recommended conservative treatment, regular attention to observation and follow-up, if there are obvious clinical symptoms, it is recommended that surgery to remove; 4, bursitis: tailbone bone has a bump very painful and may be bursitis, consider related to trauma, infection or other diseases, when occurring in and around the tailbone, can also lead to tailbone bone has a bump If it is caused by infection, local redness, swelling, heat and pain can also appear, but the caudal vertebrae are relatively rare lesions. After diagnosis, you can take oral celecoxib capsules as prescribed by your doctor, and also with acupuncture and Chinese herbal fumigation to help treat it.