a group of mostly congenital diseases of bone characterized by malformation of various parts of the skeleton. In bone dysplasias, one or more bones and sometimes the entire skeleton is affected, and the bones can be partially or completely underdeveloped. Gigantism is a type of bone dysplasia.
The commonest type is fibrous dysplasia, which usually arises in childhood or adolescence and can have a prolonged latent period. It is characterized by abnormal focal proliferation of osteogenic tissue in the bones, while the adjacent bony tissue’s structure remains normal. The affected bones are deformed; for example, tubular bones become twisted. Fractures occasionally occur and heal poorly. The course of fibrous dysplasia is chronic and generally benign.