Neonatal mastitis with abscess

Case contributed by Natalie Lawrence


12 day old male presents with asymmetrical left breast swelling with erythema and warmth of the overlying skin.

Patient Data

Age: 12 days
Gender: Male

Ultrasound Neonatal Breast


Ultrasound demonstrated a poorly defined focus of mixed echogenicity located behind the areolus. Within the mass an anechoic region is seen superficially. The mass has internal vascularity and the anechoic region has increased vascularity seen peripherally. The subcutaneous tissues are thickened, hyperechoic and also demonstrate increased vascularity. 

Right breast for comparison showing normal thickness of subcutaneous tissues and absence of hypoechoic breast bud.

Case Discussion

Neonatal mastitis and abscesses are an uncommon finding. The peak incidence is at three weeks of age. Under two weeks of age the incidence is equal amongst male and females 1. After that time there is a predilection for females.

The sonographic features of neonatal mastitis were demonstrated in this case including:

  • poorly marginated breast bud 2
  • thickened, hyperechoic and hypervascular subcutaneous fat 1
  • mass with mixed echogenicity and internal vascularity 1

The anechoic focus seen superficially within the breast tissue had no internal vascularity with peripheral hypervascularity which is suggestive of an abscess 2.

The child was treated with IV antibiotics and incision and drainage. Microbiology identified Staphylococcus aureus.

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