Fibrogenesis Imperfecta Ossium: A Collagen Defect Causing Osteomalacia

Fibrogenesis imperfecta ossium is a rare disorder that leads to generalized and progressive skeletal pain and tenderness. Radiographs show a coarsened and mottled trabecular pattern, with a spotty increase in bone density. In the third case diagnosed during life so far reported, the histologic picture and bone remodeling data obtained after a double bone-label with tetracycline demonstrated increased numbers of osteoid seams and an impaired mineralization of matrix compatible with a diagnosis of osteomalacia. There was a marked reduction in the birefringence normally seen in collagen fibers of bone under the polarizing microscope. A primary collagen defect leading to an abnormal polarization of individual collagen fibers may be the cause of the skeletal picture of osteomalacia in fibrogenesis imperfecta ossium.