What is the best approach for imaging and managing breast cellulitis after mastectomy?

Imaging Approach for Breast Cellulitis Post-Mastectomy

Ultrasound (US) is the first-line imaging modality for evaluating breast cellulitis in post-mastectomy patients, with high negative predictive value (97%) for detecting underlying malignancy or abscess. 1

Diagnostic Algorithm

Initial Imaging

1. Ultrasound (US)

   • First-line imaging modality for post-mastectomy breast cellulitis
   • Highly effective at identifying:
     • Underlying fluid collections/abscesses requiring drainage
     • Recurrent malignancy that may present with inflammatory changes
     • Fat necrosis that may mimic infection
   • Advantages: High negative predictive value (97%), no radiation, readily available 1

2. When to add diagnostic mammography/tomosynthesis

   • Only if ultrasound findings are indeterminate
   • May help characterize fat necrosis or benign calcifications
   • Limited utility as primary imaging as it detects only 56% of recurrences visible on ultrasound in patients with autologous flap reconstruction 1

Second-line Imaging (if initial workup inconclusive)

1. MRI with contrast (not without contrast)
   • Only if ultrasound findings are equivocal and there is concern for underlying malignancy
   • Must be performed with IV contrast as non-contrast breast MRI has no established diagnostic value 2
   • Note: Tissue expanders may be a contraindication to breast MRI 1

Clinical Considerations

Risk Factors for Post-Mastectomy Cellulitis

• Presence of lymphedema (significant risk factor) 3
• Longer duration of lymphedema 3
• History of radiotherapy 3
• Previous fluid collections at surgical site 4
• Recent mammography (61.5% of cellulitis episodes occurred within 3 months of follow-up mammogram) 4

Management Pearls

• Prompt antibiotic therapy is essential, even before culture results 5
• Consider anti-streptococcal coverage as empiric therapy 5
• Monitor for necrotizing fasciitis, which may require surgical debridement or partial mastectomy in severe cases 6
• Recurrent cellulitis is common (some patients experience multiple episodes) 4, 7

Pitfalls to Avoid

1. Ordering non-contrast breast MRI

   • No established role in breast imaging and provides no diagnostic value 2
   • Always order contrast-enhanced MRI if MRI is needed

2. Relying solely on mammography

   • May miss up to 44% of recurrences that are visible on ultrasound 1
   • Limited utility in post-surgical, post-radiation changes

3. Delaying antibiotics while awaiting cultures

   • Bacterial cultures are often negative despite clear clinical infection 5
   • Early antibiotic intervention is critical to prevent complications

4. Missing underlying malignancy

   • Cellulitis can mask recurrent disease
   • Persistent or recurrent cellulitis warrants thorough imaging evaluation

5. Overlooking lymphedema management

   • Proper lymphedema treatment may reduce infection risk 5, 3
   • Patients with cellulitis often require more intensive lymphedema management 3

By following this evidence-based approach with ultrasound as the primary imaging modality, clinicians can effectively evaluate post-mastectomy breast cellulitis while minimizing unnecessary radiation exposure and optimizing detection of underlying pathology that may require specific intervention.