The limited density increase of ribs is the result of imaging diagnosis, which is mainly considered to be related to inflammation, trauma, bone island and tumor in clinic. 1. Inflammation: such as tuberculosis, costal osteomyelitis and other diseases, inflammatory stimulation causes local bone destruction of the rib, and the repair process will cause calcium deposition, which will lead to sclerosis and hyperplastic changes of the rib bone, and the imaging examination can show the result of limited density increase of the rib bone. 2. Trauma: such as rib fracture tissue repair process, can lead to a large amount of calcium deposition, resulting in imaging results in limited density increase. 3. Bone island: the abnormal development of bone causes the deposition of calcium salts in the cancellous matrix of bone, resulting in a round or ovoid-shaped dense foci called bone island, which may be a congenital developmental problem or formed later in life, and generally do not require special treatment. 4. Tumor: such as rib osteoma can cause osteolytic destruction of the rib, limited density increase, and a local raised mass can appear. If the imaging suggests limited density increase of ribs, it is necessary to consult the doctor in time to make a clear diagnosis and then treat it positively, so as to avoid delaying the condition.