Breast enlargement before puberty

Summary

Breast enlargement in neonates is a common and transient condition influenced by maternal hormones. Premature thelarche describes breast development in girls occurring typically in two peaks: during the first two years of life and at six to eight years of age. Watch and wait, refer if atypical features present.

Presentation

Neonatal Breast Enlargement:

Neonatal breast enlargement is a benign proliferation of mammary gland tissue seen in approximately 70% of healthy newborns. It typically occurs in the first 1 to 2 weeks of life, and is attributed to maternal hormone influence. It spontaneously regresses within 6 months. Unilateral or bilateral enlargement can occur.

Premature Thelarche:

Premature thelarche describes breast development in girls occurring typically (but not exclusively) in two peaks: during the first two years of life and at six to eight years of age. It may be unilateral or bilateral. It is characterized by the development of a small amount of breast tissue before the age of 3 years. Although the breast may wax and wane in size, breast development in premature thelarche is non-progressive in terms of pubertal development and does not lead to other signs of puberty.

What to Do:

• Take a thorough history (including family history), perform physical examination for breast tissue and other signs of puberty (pubic hair growth, external genitalia), and plot growth chart parameters.
• Neonatal breast enlargement and premature thelarche without atypical features do not typically need investigation. In the case of premature thelarche breast size may wax and wane over time.
• Monitor the patient (eg review in 6 months) to identify any evidence of pubertal progression or accelerated growth

When to refer

• if the breast enlargement is accompanied by other concerning symptoms such as evidence of pubertal progression or accelerated growth