[Thelarche praecox in young girls: recent approaches to the pathogenesis and clinical evaluation].

Premature breast development (premature thelarche) is a common reason of referring prepubertal girls for endocrinological evaluation. It is considered as a benign condition but its pathogenesis is still unknown. It is postulated that it may be due to premature partial activation of hypothalamo-pituitary axis or to the increased sensitivity of breast tissue to normal, prepubertal estradiol levels. Although it rarely progresses to central precocious puberty the differential diagnostics is essential, as the latter pathology should be treated as early as possible. So called "exaggerated thelarche" or "telarche variant" may constitute a diagnostic challenge.