Why does a radial sclerosing lesion require surgical excision?

Why Radial Sclerosing Lesions Require Surgical Excision

Radial sclerosing lesions (RSLs) require surgical excision primarily when they are associated with epithelial atypia due to a significant risk of upgrade to malignancy (16-29%) at excision.

Understanding Radial Sclerosing Lesions

Radial sclerosing lesions, also called radial scars or complex sclerosing lesions (CSLs), are benign breast lesions that can mimic carcinoma on imaging. They have the following characteristics:

• Stellate architecture with a central fibroelastotic nidus
• Entrapped-appearing ducts and proliferative changes at the periphery
• Appearance on imaging that can resemble invasive carcinoma
• Incidence of <0.1% to 1% at core needle biopsy 1

Decision Algorithm for Management of RSLs

Step 1: Evaluate Core Needle Biopsy Results

• If RSL with atypia: Surgical excision is mandatory
• If RSL without atypia: Consider factors below

Step 2: For RSLs Without Atypia, Consider:

1. Size of lesion:

   • ≤1 cm: Lower risk of upgrade (<3%)

   • 1 cm: Higher risk of upgrade

2. Radiologic-pathologic concordance:

   • Concordant: Lower risk
   • Discordant: Surgical excision recommended

3. Biopsy method:

   • Vacuum-assisted large-core biopsy: More reliable sampling
   • Standard core needle biopsy: Less reliable sampling

Evidence Supporting Surgical Excision

According to NCCN guidelines, surgical excision is recommended for radial scars/complex sclerosing lesions diagnosed on core needle biopsy, particularly when:

1. The lesion is associated with atypia (atypical ductal hyperplasia, lobular neoplasia) 2
2. The biopsy result is indeterminate or benign but image-discordant 2
3. The lesion is of concern to the pathologist 2

The NCCN guidelines specifically state: "Other histologies that may require additional tissue samples include mucin-producing lesions, potential phyllodes tumor, papillary lesions, radial scars, or other histologies of concern to the pathologist" 2.

Risk of Malignancy Upgrade

The primary concern with RSLs is the risk of upgrade to malignancy at surgical excision:

• RSLs with associated atypia: 16-29% upgrade rate to malignancy 1
• RSLs with atypical ductal hyperplasia (ADH): 35% upgrade rate 3
• RSLs with lobular neoplasia: 11.76% upgrade rate 3
• RSLs without atypia: <3% upgrade rate, particularly when ≤1 cm 1, 4

Recent Evidence Supporting Selective Excision

Recent studies suggest that not all RSLs require excision:

• A 2024 study found that RSLs without atypia had only a 1% upgrade rate, with these upgrades being incidental findings not directly associated with the RSL 4
• A 2019 study demonstrated that vacuum-assisted large-core biopsy revealing an RSL without atypia had no upgrades to malignancy when radiological and histological findings were concordant 5

Practical Management Recommendations

1. RSLs with atypia: Always perform surgical excision due to high upgrade rates (16-29%)

2. RSLs without atypia:

   • Consider observation with imaging follow-up if:
     • Lesion is ≤1 cm
     • Adequate sampling was performed (vacuum-assisted biopsy)
     • Radiologic-pathologic findings are concordant
   • Recommend surgical excision if:
     • Lesion is >1 cm
     • Associated with architectural distortion on imaging
     • Residual calcifications/architectural distortion on post-biopsy mammogram
     • Inadequate sampling or radiologic-pathologic discordance

Follow-up Protocol if Excision is Deferred

If surgical excision is not performed:

• Physical examination with or without ultrasound/mammogram every 6-12 months for 1-2 years
• Return to routine screening if the lesion remains stable
• Proceed to surgical excision if the lesion increases in size or suspicion

By carefully evaluating the presence of atypia, size, and radiologic-pathologic concordance, clinicians can determine which radial sclerosing lesions require surgical excision to prevent missing potential malignancies while avoiding unnecessary surgery in low-risk cases.