Chapter 162 - Common Skeletal Deformities

Abstract

The disorders discussed here reflect localized disturbances of the endochondral growth plate development or localized disturbances of bone maturation. In the first category are dysplasia epiphysealis hemimelica, hereditary multiple exostoses and its variant Langer–Giedion syndrome, and enchondromatosis and its variants Maffucci syndrome and metachondromatosis. They are due to asymmetrical, displaced, or aberrant growth of endochondral cartilage tissues that interferes with normal skeletal development and which may occur as an isolated finding or in concert with other disease manifestations. Some conditions are inherited, but others occur sporadically. The second category comprises fibrous dysplasia of bone, which can be monostotic or polyostotic as an element of McCune–Albright syndrome, and cherubism. Fibrous dysplasia results from somatic activating mutations of GNAS1, which produce McCune–Albright syndrome if they occur early in development or isolated bone lesions if they occur later. Cherubism, which is characterized by painless symmetrical swelling of the jaws during childhood, results from heterozygous mutations of the adaptor protein SH3BP2.