Breast Abscess



  • Breast abscess: localized accumulation of infected fluid within the breast parenchyma
  • Mastitis: breast inflammation with or without infection; this can be associated with lactation (puerperal) or nonlactational.
  • Associated with lactation or fistulous tracts secondary to squamous epithelial neoplasm or duct occlusion
  • System(s) affected: skin/exocrine, immune
  • Synonym(s): mammary abscess; peripheral breast abscess; subareolar abscess; puerperal abscess

Pregnancy Considerations
Most commonly associated with postpartum lactation


  • Most common benign breast problem during pregnancy and puerperal period (1)
  • Predominantly reproductive age and perimenopausal (between ages 18 and 50 years)
    • Puerperal abscess: lactational
    • Subareolar abscess: reproductive age through postmenopause (2)
      • 90% of nonlactational breast abscesses are subareolar (1).
  • Predominant sex: female
  • Higher incidence in African American, diabetic, tobacco use, or obese women

Ranges between 3% and 11% of women with mastitis (1),(3)

Transient condition usually as a complication of mastitis; mastitis prevalence ranges between 1% and 10% (1).

Etiology and Pathophysiology

  • Puerperal abscesses:
    • Associated with hyperlactation and dysbiosis (disrupted milk microbiome); these can lead to ductal narrowing and inflammation and subsequently to reduced milk flow, obstruction, plugged lactiferous duct causing stasis, microbial growth, and infection (3).
    • Mammary dysbiosis is a consequence of multiple factors including genetic, breastfeeding-related, medical, and microbial (3).
    • Likely that bacteria (often from infants oral flora) gain entry through cracks/fissures in the nipple (1)
    • Insufficient treatment of mastitis
    • Unattended postpartum engorgement and other situations leading to breast milk stasis (3)
  • Subareolar abscess:
    • Associated with squamous metaplasia of the lactiferous duct epithelium, keratin plugs, ductal ectasia, and fistula formation (2)
  • Microbiology
    • Staphylococcus aureus is the most common cause of lactational abscesses (1),(2).
    • Methicillin-resistant S. aureus (MRSA) is a significant cause (1).
    • Other common causes include coagulase-negative staphylococci and Streptococcus spp. (2),(3).
    • Less common causes (1):
      • Escherichia coli, Enterobacteriaceae, Corynebacterium, and Pseudomonas
      • Anaerobes
      • May be polymicrobial

Maternal genetics may play a role as protective and predisposing factors for mammary dysbiosis, which is associated with the pathophysiology (3).

Risk Factors

  • Smoking, maternal age >30 years
  • Primiparous, pregnancy ≥41 weeks’ gestation
  • Diabetes and obesity
  • African American
  • Nipple piercing
  • Milk stasis:
    • Infrequent or missed feeds
    • Poor latch, weak or uncoordinated suckling
    • Damage or irritation of the nipple, nipple inversion or retraction
    • Inefficient removal of milk (by baby or pump), oversupply of milk
    • Illness in mother or baby, rapid weaning, plugged duct
    • Pressure on the breast (i.e., tight bra, car seatbelt)
    • Maternal stress and fatigue
  • Medically related risk factors
    • Steroids
    • Breast implants
    • Lumpectomy with radiation
    • Inadequate antibiotics to treat mastitis
    • Topical antifungal medication used for mastitis

General Prevention

  • Frequent breast emptying with on-demand feeding and/or pumping to prevent mastitis
  • Early treatment of mastitis with milk expression, antibiotics, and compresses
  • Smoking cessation to minimize occurrence/recurrence

Commonly Associated Conditions

Lactation, mastitis, weaning

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