An 11-month-old girl with central precocious puberty caused by hypothalamic hamartoma.

Central precocious puberty (CPP) is caused by premature activation of the hypothalamic-gonadal axis, and must be treated adequately. In particular, CPP that occurs at a relatively young age or in boys is likely to be caused by an organic lesion. Hypothalamic hamartoma (HH) is the most common organic cause of CPP. The present case report describes an 11-month-old female infant who presented with vaginal bleeding and rapidly progressive secondary sex characteristics from the age of 6 months. She was diagnosed with CPP following the detection of HH via magnetic resonance imaging. The infant girl was successfully treated with gonadotropin-releasing hormone agonist. After 6 months, her breast had regressed and clinical and radiological follow-up demonstrated stable findings with no evidence of tumor growth or secondary sexual characteristics until the fourth year after the initiation of treatment. This patient is the one of the youngest infants presenting with CPP and HH in Korea; treatment was successful over a relatively long follow-up period.