Clinical History
A female neonate presented with bilateral breast swelling, which was slightly more pronounced on the left side. There was mild redness of the skin of the left breast since birth, but absence of fever or local tenderness.
Imaging Findings
Ultrasound examination of the neonatal breast showed ovoid-shaped masses (Fig. 1) in the retroareolar region of both breast, consisting of central echogenic tissue surrounded by numerous peripheral cysts of variable size. No debris, septations or fluid-fluid levels were seen. There was no increased vascularity and the overlying skin was normal. Surrounding tissues were normal. The lesions measured about 4.4 x 3.2 cm and 4.5 x 4 cm in diameter on the right and left side respectively.
Follow up ultrasound of the breast after two months (Fig. 2) showed significant regression of the abnormalities seen in the retroareolar regions that appeared as irregular asymmetric hypoechoic areas being more prominent on the left side. Ultrasound repeated after six months (Fig. 3) demonstrated only small residual hypoechoic tissues in the retroareolar region resembling breast buds; no other abnormalities were seen.
Discussion
Normal breast development undergoes two stages of growth. The first stage occurs during fetal development and leads to the formation of a rudimentary breast tissue consisting of simple-branched ducts which are able to respond to the hormonal stimulation of maternal origin. [1] The second stage of growth occurs at adolescence in response to release of many hormones ended by the formation of fully developed breast. Neonatal breast enlargement under the nipple area due to glandular proliferation is common and almost always benign. It equally affect both sexes and is believed to be due to exaggerated response to maternal oestrogen hormone crossing through the placenta to the fetal circulation in the uterus [2]. This response is noticed, leading to breast enlargement, and the reason is not known.
Neonatal breast enlargement is asymptomatic in 60% -90% and found to be a soft subareolar mass or thick subcutaneous tissue and sometimes may appears hard, tender with hyperaemia that are often mistaken for breast mastitis. It may be unilateral or bilateral, but more frequently bilateral [3]. Neonatal breast enlargement may be seen at birth and might even continue to grow after birth in the first weeks of life and sometimes spontaneous breast discharge occurs [4].
Over weeks or months, when the exposure to maternal hormones decreases, the breast tissue begins to shrink and eventually becomes quite flat. Occasionally a normal, small amount of tissue remains. Reassurance of the parents is the only necessary management of neonatal breast enlargement [5].
This process is different from benign premature thelarche that represent an isolated breast development in females aged 6 months to 9 years due to subtle overfunction of the pituitary-ovarian axis. If no other signs of puberty are present, reassure the family that this is a benign finding.
US is the ideal imaging modality to study the neonatal and paediatric breast and can be useful in detection and characterizing the breast abnormality and help in further management. Knowledge of the US appearance of normal breast development and specific lesions is essential for successful use of breast US [6].
We report this case to draw attention to the peculiar sonographic appearance of hormone-related neonatal breast enlargement.
Correct interpretation of the clinical and imaging findings is required, as the lesion is transient and needs no further treatment.
Differential Diagnosis List
The diagnosis of benign neonatal breast enlargement was made.
Based on the clinical findings and ultrasound appearance
no differential diagnosis was given
Final Diagnosis
The diagnosis of benign neonatal breast enlargement was made.
