A 9-year-old girl presents for evaluation of regular vaginal bleeding. History reveals thelarche at the age of 7 and adrenarche at the age of 8.
Which of the following is the most common cause of this condition in girls?A. Idiopathic
In North America, pubertal changes before the age of 8 years in girls and 9 years in boys are regarded as precocious. Although the most common type of precocious puberty in girls is idiopathic, it is essential to ensure close long-term follow-up of these patients to ascertain that there is no serious underlying pathology, such as tumors of the CNS or ovary. Only 1% to 2% of patients with precocious puberty have an estrogen-producing ovarian tumor as the causative factor. McCune-Albright syndrome (polyostotic fibrous dysplasia) is also relatively rare and consists of fibrous dysplasia and cystic degeneration of the long bones, sexual precocity, and café au lait spots on the skin. Hypothyroidism is a cause of precocious puberty in some children, making thyroid function tests mandatory in these cases. Tumors of the CNS as a cause of precocious puberty occur more commonly in boys than in girls; they are seen in about 11% of girls with precocious puberty.