Neonatal mastitis

Last revised by Mostafa El-Feky on 26 Nov 2022

Neonatal mastitis is rare and refers to infection of the breast tissue occurring in a neonate.

Patients may present with unilateral breast erythema and pain sometimes with associated nipple discharge and lymphadenopathy. It usually occurs in patients under five weeks of age, with a peak incidence around three weeks of age. Systemic symptoms, such as fever, are not always present.

Neonatal breast hypertrophy is common in newborns, which is thought to be from declining levels of maternal estrogen triggering neonatal prolactin secretion. Superinfection of this breast tissue results in mastitis.

The most common causative organisms are Staphylococcus aureus (83-88% of cases), Escheria coli, Salmonella spp., anaerobes and Group B streptococcus. 

  • poorly defined hyperechoic breast tissue with hyperemia with surrounding hypervascular, hyperechoic subcutaneous fat

  • abscesses may appear as avascular hyperechoic or anechoic areas with surrounding hyperemia

Oral or parenteral antibiotic therapy is usually required.

  • breast abscess formation is the main complication from neonatal mastitis; incision and drainage may be necessary in these complicated cases

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Cases and figures

  • Case 1: neonatal mastitis with abscess
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