McCune-Albright syndrome, a rare form of precocious puberty: diagnosis, treatment, and follow-up

INTRODUCTION: McCune-Albright syndrome (MAS) is a genetic disorder defined by fibrous dysplasia of bone, café-au-lait skin spots, and autonomous hyperfunction of one or more endocrine organs. MAS is caused by activating mutations of the GNAS1 gene. The most frequent type of endocrinopathy is gonadal endocrinopathy in the form of peripheral precocious puberty. OBJECTIVE: To describe the clinical characteristics, laboratory and imaging tests at the time of diagnosis and over the course of the disease, focusing on the classical triad of MAS. POPULATION AND METHODS: Observational, descriptive, retrospective clinical study of patients with MAS seen at the Department of Endocrinology of Hospital de Niños Ricardo Gutiérrez between 1974 and 2019. RESULTS: Twelve girls are described, all of whom developed peripheral precocious puberty (PPP) secondary to functional ovarian cysts. Their age at presentation was early (2.6 ± 1.3 years). Gonadotropin levels were suppressed or in the prepubertal range with generally high estradiol levels. Ten girls had café-au-lait skin spots since birth. During the course of disease, polyostotic fibrous dysplasia was detected in all patients. The treatments used to reduce ovarian cyst recurrence and hyperestrogenism effects showed varied effectiveness. CONCLUSIONS: In this series, the onset of PPP helped to make an early diagnosis of MAS and was difficult to treat. The course of disease showed persistent gonadal hyperfunction and worsening of bone injuries.