What is the best course of treatment for a non-breastfeeding woman presenting with signs of breast infection?

Management of Breast Infection in Non-Lactating Women

In a non-breastfeeding woman with signs of breast infection, you must first rule out inflammatory breast cancer or other malignancy before treating as simple infection, particularly in older women, as inflammatory breast cancer can mimic mastitis and requires urgent oncologic management. 1, 2

Initial Diagnostic Approach

Immediate Red Flags Requiring Malignancy Workup

• Age matters critically: Inflammatory breast cancer typically occurs in older women, while acute mastitis usually affects younger, lactating women 2
• Clinical presentation requiring biopsy: Dermal edema (peau d'orange), breast erythema involving one-third or more of the breast with a palpable border, or any unusual skin changes mandate evaluation for inflammatory breast cancer 1
• Nipple changes: Excoriation, scaling, or eczema should raise suspicion for Paget's disease of the breast 1

Required Initial Imaging

• Bilateral diagnostic mammogram with or without ultrasound is the first step for any non-lactating woman with breast infection signs 1
• Ultrasound should be performed to identify abscesses in immunocompromised patients or those with worsening/recurrent symptoms 3
• Antibiotics should not delay diagnostic evaluation, even if clinical suspicion for infection exists 1

When Imaging is Normal (BI-RADS 1-3)

• Punch biopsy of the skin should still be performed after normal imaging to exclude inflammatory breast cancer or Paget's disease 1
• If biopsy is benign but clinical suspicion remains: Consider breast MRI, repeat biopsy, and consultation with a breast specialist 1

When Imaging is Abnormal (BI-RADS 4-5)

• Core needle biopsy is the preferred option with or without punch biopsy, though surgical excision is also acceptable 1
• If core biopsy is benign: Still perform punch biopsy of the skin if not previously done 1

Antibiotic Treatment (Only After Malignancy Excluded)

Underlying Conditions to Identify

• 60% of non-lactating breast infections have underlying pathology: Granulomatous mastitis (50%), duct ectasia (15%), pregnancy (12%), diabetes (12%), fat necrosis (4%), or breast cancer (8%) 4
• These underlying conditions must be identified and treated in addition to the infection 4

Antibiotic Selection

• First-line antibiotics: Cephalexin or dicloxacillin to cover Staphylococcus aureus, the most common organism 5, 6
• Broader coverage may be needed: Non-lactating infections can involve uncommon organisms including Klebsiella pneumoniae, Peptococcus magnus, Streptococcus group B, Enterobacter cloacae, MRSA, and Mycobacterium tuberculosis 4
• Obtain milk cultures or aspirate cultures to guide antibiotic therapy, especially if initial treatment fails 3

Conservative Measures

• 1-2 day trial of conservative management before antibiotics: NSAIDs, ice application 3
• Avoid aggressive interventions: Excessive pumping, heat application, and aggressive breast massage can worsen the condition 3

Abscess Management

• Approximately 10% of mastitis cases progress to breast abscess requiring drainage 7
• Surgical drainage or needle aspiration is required once an abscess develops 6
• Ultrasound guidance facilitates aspiration and confirms complete drainage 3, 8

Critical Pitfall

If antibiotics do not decrease signs and symptoms within 48-72 hours, inflammatory breast cancer must be reconsidered, especially in older, non-lactating women 2. This is not simple treatment failure—it demands immediate return to diagnostic workup with biopsy 1.