Physiological neonatal breast enlargement

Case contributed by Ashesh Ishwarlal Ranchod
Diagnosis almost certain


Asymmetric left breast enlargement in an infant.

Patient Data

Age: 4 months
Gender: Female

There is unilateral (left-sided), asymmetric, heterogeneous, retroareolar tissue measuring 20.4 x 7.1 x 22.7 mm. There is no evidence of neonatal mastitis. There is normal age-appropriate contralateral right breast tissue.

Case Discussion

Features consistent with unilateral, physiological, left breast enlargement in a 4-month-old child.

Conservative management was recommended.

Physiological neonatal breast enlargement is caused either by an exaggerated response to maternal estrogen that has entered the fetal circulation through the placenta or pituitary secretion of prolactin near the end of pregnancy as a response to declining estrogen levels in the maternal circulation. It is more frequently bilateral. Resolution is expected at 6 months of age, although it can take longer than that.

Sonographer: E Mbuyane

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