ABSTRACT
Idiopathic hyperphosphatasia is a rare autosomal recessive bone disorder, characterized
by excessive bone resorption and bone formation. The radiographic appearances include
widening of the diaphyses, vertebral osteoporosis, acetabular protrusion, and thickening
of the skull vault. There is considerable variability in phenotype, with some cases
diagnosed in infancy and others in later childhood. Most cases appear to arise from
inactivating mutations in the gene encoding osteoprotegerin, a product of osteoblasts
that is critically involved in osteoclastogenesis. Treatment with inhibitors of bone
resorption (calcitonin or bisphosphonates) is successful in ameliorating some aspects
of the disorder.
KEYWORD
Hyperphosphatasia - juvenile Paget's disease - osteoprotegerin - hyperostosis
