Paget's disease of bone - Pathogenesis and causes

They described three phases of Paget's disease. This phase starts with the lithic, bone resorption with increased osteoclast abnormalities detected at bone damage. These osteoclasts are more numerous and have more nuclei, up to 100 from the normal number of 5-10 nuclei. These abnormalities of bone turnover increases 20 times than normal. The significant increase in bone resorption leads to the second phase known as the mixed phase of rapid growth of bone formation with numerous osteoblasts, morphologically normal. Newly formed bone is abnormally formed collagen fibers are deposited abnormally.In the final phase of Paget's disease, also known as sclerotic phase, bone formation and this is dominating the abnormal form, foam and much worse than resistance. This model allows bone marrow to be infiltrated by excessive connective tissue fibers and blood vessels leading to hipervascularizatie.
Paget's disease can be monostotic, but is more frequently multifocal, with predilection for the axial skeleton: spine, pelvis, femur, sacrum and skull. Any bone can be affected, however. After onset Paget's disease of the bone does not extend to the bone, but can become progressive and worsen pre-existing location.Impaired spinal Paget's disease is associated with complications including nerve root compression syndrome ponytail. Fractures are the most common complications of the disease have potentially devastating consequences. Less bone sarcomatous transformation of Paget's suffering.
Although the etiology is unknown and genetic factors have been proposed of the environment. Etinice and geographic clusters of disease are well known. Paget's disease is common in Europe, North America, Australia and rare in Asia and Africa.Approximately 40% of patients described a family history of disease. Some studies suggest a genetic link to chromosome arm 18q disease, although this has not been demonstrated in many families with Paget's disease, suggesting genetic heterogeneity.An exogenous factor was considered but never proved in the pathogenesis of the disease. The results of bone biopsies from patients with Paget's disease show different Paramyxoviridae viral antigens, including chicken pox and respiratory syncytial virus, localized in osteoclasts. However trigger antigen still remains unknown.