Classically, McCune-Albright syndrome has been defined by the clinical triad of polyostotic fibrous dysplasia of bone (FD), café-au-lait skin spots, and precocious puberty (PP). It is a rare disease, of which the precise prevalence is not known. In addition to PP, other hyperfunctioning endocrinopathies may be involved including hyperthyroidism, growth hormone excess, Cushing's syndrome, and renal phosphate wasting. Café-au-lait spots usually appear in the neonatal period, but it is usually precocious puberty or FD that brings the child to medical attention. The disease results from somatic mutations of the GNAS gene, specifically mutations in the cAMP regulating proteine, Gsα. The stage and location within the developing organism at which the spontaneous mutation occurs may determine the phenotype, i. e. the earlier the mutation occurs, the more extensive the disease.
The evaluation of patients with this condition should be guided by knowledge of the spectrum of tissues that may be involved, with specific testing for each. Treatment is dictated by the tissues affected, and the extent to which they are affected. Specifics of the subtleties of diagnosis and treatment are discussed.