High density foci of ribs are usually the result of X-ray examination, which may be caused by trauma, bone marrow fibrosis, or fluorosis. 1. Physiological factors: patients who have suffered from trauma resulting in rib fractures, in the process of fracture healing will form a bone crust, usually the density of the bone crust is higher than the density of the rib bone, so there will be a high-density foci of the rib bone. 2. Myelofibrosis: a myeloproliferative disease in which the proliferating fibrous tissue replaces the hematopoietic tissue due to various reasons. The disease may have no obvious symptoms at the early stage, but in severe cases, bones and bleeding may appear, and high density foci of ribs may appear in the imaging examination. 3. Fluorosis: a kind of chronic bone disease caused by chronic fluorosis and bone abnormally dense, hardening, the emergence of mottled enameled teeth, limbs, spine pain and deformation, patients with fluorosis can also be manifested as the symptoms of high density foci of the ribs. If the examination found that the rib bone high density foci, should promptly consult the doctor, identify the cause of the disease, and actively treat.