Fibrogenesis imperfecta ossium (Baker’s disease): a case studied at autopsy

A man aged 40 years showed radiographic changes in the form of generalized increased bone density and patchy rarefaction. Urinary calcium was increased and serum alkaline phosphatase was elevated; serum calcium and phosphate levels were normal. Multiple fractures developed. At autopsy, all parts of the skeleton showed partial replacement of bone and bone marrow by a tissue deficient in collagen fibers. Much of this tissue was unmineralized, but lesions in cortical bone showed hypermineralization on microradiographic examination. Electron microscopy showed replacement of collagen fibers by amorphous material in the affected areas. Electron probe analysis showed a normal Ca:P ratio for bone mineral in the hypermineralized areas.