Fibrous dysplasia (FD) is a rare non-hereditary skeletal disease in which abnormal fibrous tissue replaces bone tissue. It is due to a mutation in the GNAS gene that alters the differentiation of skeletal stem cells into mature osteoblasts. Osteoclastogenesis is also strongly activated, due to the presence of numerous cytokines and factors that promote this process. The resulting bone is poorly mineralized, with an excess of extracellular matrix, and predisposed to fractures and deformities. Lesions can affect only one bone, several bones, or occur in association with hyperfunctioning endocrinopathies and hyperpigmentation of the skin, which may already be present at birth and in severe cases can lead to death (FD/McCune-Albright syndrome [MAS]). The clinical spectrum is extremely complex. To date, there is no pharmacological treatment to prevent the appearance of FD lesions or slow their course. Therefore, the purpose of this concise review is to provide a general overview of current knowledge about FD/MAS and its clinical manifestations, in order to find new molecules useful for the future development of drugs.
KEY WORDS: Fibrous dysplasia, McCune-Albright syndrome, rare disease, bone disorders.
