McCune-Albright syndrome (MAS) is a nonhereditary condition characterized by multiple thickened areas of bone (polyostotic fibrous dysplasia), irregularly shaped splotches of increased skin pigmentation, and extremely early onset of puberty (precocious puberty). The skin findings are usually present at birth or appear within the first few months of life. Bony abnormalities become evident during childhood and are usually progressive. Pubertal changes may occur as early as 4 months of age, but the average age of their appearance is 3 years.
A hereditary syndrome observed in females is marked by the emergence of ovarian cysts and premature onset of puberty, transpiring prior to the age of eight. This condition is accompanied by deviations in bone composition and alterations in pigmentation of the skin.