What's the next step for a patient with two adjacent iso-to hypoechoic subcentimeter masses in the left breast with a low suspicion for malignancy (2-10% likelihood)?

Ultrasound-Guided Core Biopsy for Breast Masses with Low Suspicion for Malignancy

The next step for this patient with two adjacent iso-to hypoechoic subcentimeter masses in the left breast with a low suspicion for malignancy (2-10% likelihood) should be to proceed with the recommended ultrasound-guided core biopsy. 1

Rationale for Core Biopsy

• The NCCN guidelines specifically recommend ultrasound-guided core biopsy as the appropriate next step for BI-RADS category 4 findings (suspicious for malignancy), which includes category 4A lesions with 2-10% likelihood of malignancy 1
• The finding of "indistinct margins" in these masses is particularly concerning and warrants tissue sampling rather than observation, even with the relatively low suspicion for malignancy 2
• Short-term follow-up imaging is not appropriate for BI-RADS 4 lesions, as the 2-10% risk of malignancy is too high to delay diagnosis 1

Advantages of Ultrasound-Guided Core Biopsy

• Core needle biopsy is superior to fine-needle aspiration (FNA) in terms of sensitivity, specificity, and correct histological grading 1
• Provides sufficient tissue for histologic diagnosis and hormone-receptor testing if malignancy is found 1
• Allows for placement of a marker clip to identify the biopsied area for future reference 1
• Does not require breast compression, making it more comfortable for patients 1
• High diagnostic accuracy with sensitivity of 96.3% for the diagnosis of breast cancer 3

Procedure Details

• The procedure should be performed using a high-resolution, real-time linear-array scanner with an adjustable focal zone and a transducer with a minimum center frequency of 10 MHz 1
• A post-biopsy marker clip should be placed with post-procedure imaging to confirm tissue sampling of the lesion 1
• Documentation should include correlation between the imaging finding and the biopsied lesion 1

Important Considerations

• Radiologic-pathologic correlation is essential following the biopsy to ensure concordance between imaging findings and pathology results 3
• If there is discordance between radiologic and pathologic results, repeat biopsy or surgical excision may be necessary 3
• For solid masses with a BI-RADS category 4, observation is not an option, even if clinical suspicion is low 2

Potential Complications

• While rare, pseudoaneurysm formation is a potential complication of core needle biopsy that clinicians should be aware of 4
• Other potential complications include bleeding, infection, and pneumothorax, though these are uncommon

The ultrasound-guided core biopsy approach is supported by multiple studies showing high sensitivity (93.2-100%) for both palpable and non-palpable breast masses 5, 6. This approach provides definitive tissue diagnosis while avoiding unnecessary surgical excision for benign lesions.