Isolated Premature Thelarche
Premature thelarche is a benign, self-limiting condition which is characterised by breast development with no other signs of sexual maturation. There is no pubic or axillary hair development, behaviour is normal, growth is normal and the skeletal age is appropriate. The breast development has atypical appearance with relatively immature nipple development and is never more than Tanner Breast Stage III. Breast development is usually asymmetrical and the breasts increase and decrease in size at about 6-weekly intervals. The condition tends to resolve after about 1–2 years and then the onset of normal puberty occurs at the appropriate age and in the normal way. Very occasionally, vaginal bleeding can occur. There have been some reports of women who have had premature thelarche as a child developing large follicular cysts during their menstrual cycles and, thereby, having reduced fertility. However, this has not been substantiated and what limited follow-up has been achieved in further series suggests that there are no long-term sequelae. Isolated premature thelarche is a relatively common condition. It is characterised by FSH dominance and overnight gonadotrophin secretion, which is characterised by single FSH pulses. On ultrasound the ovaries are small, but often contain large follicular cysts, which increase and decrease in synchrony with the breast development.

There may well be two types of premature thelarche. The classical type commences during the first year of life and tends to resolve by the age of 2.

There is a second form of premature thelarche, of which the age of onset is over 2 years of age and this tends to be more persistent and with a higher incidence of uterine bleeding. In this ‘non-classical’ form of premature thelarche, it may well be associated with progression to gonadotrophin-dependent precocious puberty. Isolated premature thelarche is a condition which is easy to diagnose clinically and requires no treatment.