McCune-Albright syndrome onset with vaginal bleeding.

McCune-Albright syndrome (MAS), a rare genetic disorder, affects multiple organs and classically presents with the triad of polyostotic fibrous dysplasia (FD), skin hyperpigmentation (café-au-lait spots) and precocious puberty. Diagnosis occurs when patients manifest at least two of these three symptoms. We describe a 4-year-old girl who was admitted to our hospital due to recurrent vaginal bleeding, initially diagnosed as precocious puberty. On brain MRI, abnormalities in the maxillary and occipital bones were compatible with FD. Clinical examination after craniofacial bone lesions and clinical signs indicated MAS revealed abnormally pigmented macules on the neck and back, which were initially overlooked. No abnormal hormone tests were observed. Precocious puberty is the most common MAS-associated symptom that results in the admission to the hospital, whereas the clinical manifestation of FD in the first years of life is usually equivocal and probably has not been discovered by parents. Thus, comprehensive medical examinations are necessary to obtain a prompt and proper diagnosis.