Breast Ultrasound is the Appropriate Next Step
For an elderly female with a new palpable breast lump and a recent negative mammogram, proceed directly to targeted breast ultrasound rather than repeating mammography. 1, 2
Rationale for Ultrasound Over Repeat Mammography
The ACR Appropriateness Criteria explicitly state that ultrasound should be performed as the next step after a negative mammogram in women with a palpable mass, with a rating of 9 out of 9 (usually appropriate). 1 In contrast, repeat diagnostic mammography receives a rating of only 1 out of 9 (usually not appropriate) in this scenario. 1
Evidence Supporting Ultrasound Superiority
Ultrasound detects 93-100% of breast cancers that are occult on mammography in women with palpable masses, making it far more sensitive than repeat mammography for interval findings. 1, 2, 3
A 2016 study of 618 palpable lumps with recent negative mammograms found that ultrasound detected findings in 50.3% of cases, while repeat mammography detected changes in only 12.9% of cases (p < 0.001). 4
Of the 314 cases with imaging findings in that study, 234 findings (74.5%) were detected by ultrasound alone, while repeat mammography identified only 3 additional cases with no sonographic correlate—none of which were malignant. 4
The combined negative predictive value of mammography and ultrasound together exceeds 97% when both are benign, providing strong reassurance when clinical examination is not highly suspicious. 1, 2
Critical Clinical Algorithm
Step 1: Order Targeted Breast Ultrasound
- Perform ultrasound with direct correlation to the palpable finding, using the examiner's hand to guide probe placement over the exact clinical concern. 1, 2
Step 2: Act Based on Ultrasound Findings
If ultrasound shows a suspicious finding (BI-RADS 4-5):
- Proceed immediately to ultrasound-guided core needle biopsy (not fine-needle aspiration, as core biopsy is superior for sensitivity, specificity, and histological grading). 1, 2, 3
If ultrasound shows a probably benign finding (BI-RADS 3):
- Consider short-interval follow-up ultrasound at 6 months, then every 6-12 months for 1-2 years. 3
- However, in elderly patients or those with high clinical suspicion, proceed directly to biopsy rather than surveillance. 3
If ultrasound shows clearly benign features (BI-RADS 1-2):
- Simple cysts, benign lymph nodes, lipomas, or hamartomas require only clinical follow-up with no further imaging. 1, 2, 3
Step 3: Critical Exception—Do Not Ignore Clinical Suspicion
If the physical examination remains highly suspicious despite negative imaging, proceed to palpation-guided biopsy regardless of imaging results. 1, 2 This is the most important pitfall to avoid, as 10-24% of breast cancers can have negative mammography, and even combined negative mammography and ultrasound does not rule out malignancy when clinical examination is concerning. 5, 6
Why Not Repeat Mammography?
Repeat mammography within months of a negative study has extremely low yield for detecting interval changes, particularly for palpable masses which are better characterized by ultrasound. 4
Mammography is particularly effective for detecting microcalcifications and architectural distortion, but these features are rarely the cause of a new palpable lump. 1
The ACR guidelines explicitly state there is no role for repeat mammography or short-interval mammographic follow-up for women over 40 with palpable masses and negative mammographic findings. 1
A 2003 systematic review concluded that diagnostic mammography does not help determine whether a palpable breast mass should be biopsied and should not affect the decision to perform a biopsy. 6
Common Pitfalls to Avoid
Never perform biopsy before ultrasound, as biopsy-related changes will obscure and limit subsequent imaging interpretation. 1, 2
Never rely on the recent negative mammogram alone to provide reassurance—56.9% of women with palpable lumps and normal mammograms do not receive adequate evaluation, and 1.4% are subsequently diagnosed with cancer. 7
Never order MRI, PET, or molecular breast imaging as the next step, as these have no role in the initial workup of a palpable mass. 1, 2
Never delay evaluation based on the timing of the recent mammogram—the presence of a new palpable finding supersedes the recent negative imaging and mandates immediate ultrasound evaluation. 4, 8