G577(P)\u2005Precocious puberty in a five-year-old girl

Abstract

Aims McCune-Albright syndrome (MAS) is rare. It is caused by a spontaneous mutation of GNAS gene that causes dysregulation of cAMP-regulating protein Gs alpha. This affects growth and hormone production. It is characterised by a triad of café-au-lait spots, fibrous dysplasia (FD) and hyper-functioning endocrinopathies. The severity of disease and prognosis is dependent on the degree of mosaicism. Diagnosis is made clinically but can be confirmed with bone imaging and genetic testing. MAS usually presents in early childhood with precocious puberty or bone pain. In young children presenting with vaginal bleeding, sexual abuse may often be considered as a differential diagnosis. Methods A five-year-old girl presented to her GP with vaginal bleeding. She was previously well with no abdominal pain but occasional leg pains. There were no allegations of sexual abuse or trauma. The GP initially raised concerns with the local safeguarding consultant and the child was admitted to hospital for assessment. Observations were normal and systems examination was unremarkable except for precocious pubertal signs. There was dried blood on her undergarments but no signs of injury or discharge from the vagina. She had a large 25\u2009cm by 25\u2009cm café au lait spot on the left side of her back that had been present since birth. She had faint pubic hair and breast changes. Her tanner staging was B3 P2 A1. Results Ultrasound pelvis showed a large uterus with a 12\u2009mm follicle in the right ovary. Oestrodiol and prolactin levels were high with prepubertal gonadotropins. Bone scan revealed early fibrous dysplastic changes in the left humerus and her skeletal age was eight years. Genetics showed mosaicism of the GNAS gene consistent with MAS. Conclusion Although it is vital to consider safeguarding, a thorough history and clinical examination should be undertaken and differential diagnoses considered. When MAS is suspected, bone imaging to look for fibrous dysplasia, hormonal investigations and genetic testing should be considered. There is no specific treatment for MAS itself but the associated endocrinopathies may respond to treatment with hormone analogues. FD may require surgical intervention and bisphosphonates have value in fracture prevention and pain management.