A bulge in the middle of the rib cage may be caused by bone scab after fracture, costochondritis, rib tumor and so on. 1. Bone scab after fracture: there may have been a fracture here before, in the process of recovery from the fracture, the fracture site will produce a large number of bone scabs, which is locally manifested as a rib bulge. 2. Costochondritis: In costochondritis, the rib cartilage is enlarged and bulging, which will also lead to localized bulging symptoms, but the pain in the bulging area is obvious, and the pain is aggravated when coughing or taking a deep breath. 3. Rib tumor: when rib tumor occurs, there will be a raised lump locally, which may be accompanied by pain, fracture and other symptoms. If this symptom occurs, you should go to the hospital in time, complete the relevant examination to clarify the cause, and take symptomatic treatment under the doctor’s guidance.