Malignancy Rate of Architectural Distortion on Mammography
Approximately 75% of architectural distortions classified as suspicious (BI-RADS 4-5) on mammography prove to be malignant, though this rate varies substantially based on detection context and imaging characteristics. 1
Overall Malignancy Rates
The positive predictive value for malignancy when architectural distortion is deemed suspicious enough to warrant biopsy is 74.5% based on a large 10-year retrospective study of 369 biopsied cases. 1 This represents architectural distortions classified as BI-RADS 4 (suspicious) or BI-RADS 5 (highly suggestive of malignancy). 2
It is critical to understand that this 75% malignancy rate applies only to architectural distortions already determined to be suspicious—not to all architectural distortions detected on mammography. 1 Many architectural distortions are clearly benign (BI-RADS 2) when related to prior surgery or other obvious benign causes. 2
Key Factors That Modify Malignancy Risk
Detection Context
Diagnostic mammography: Architectural distortion detected during diagnostic workup (typically for symptoms or callback from screening) has an 83.1% malignancy rate. 1
Screening mammography: Architectural distortion detected on routine screening has a 67.0% malignancy rate, significantly lower than diagnostic detection (p < 0.001). 1
Ultrasound Correlation
With ultrasound correlate: When architectural distortion has a corresponding finding on ultrasound, the malignancy rate is 82.9%. 1
Without ultrasound correlate: When no sonographic abnormality is identified at the site of architectural distortion, the malignancy rate drops dramatically to 27.9% (p < 0.001). 1
For DBT-detected architectural distortions with no ultrasound correlate showing benign pathology without atypia on core needle biopsy, the upgrade rate to malignancy is 0%, supporting imaging surveillance as an alternative to surgical excision. 3
Associated Imaging Features
- Pure architectural distortion versus architectural distortion with calcifications or asymmetries: No statistically significant difference in malignancy rates (73.0% vs 78.8%, p = 0.26). 1
Pathologic Outcomes When Malignant
Invasive adenocarcinoma is the most common malignant diagnosis when architectural distortion proves to be cancer. 1
Ductal carcinoma in situ (DCIS) alone accounts for only 4.1% of malignant architectural distortions, meaning the vast majority of malignant cases are invasive. 1
Pathologic Outcomes When Benign
Radial scar or complex sclerosing lesion is the most common benign finding, accounting for 7.3% of biopsied architectural distortions. 1
Radial scars without atypia at initial biopsy have an extremely low upgrade rate to malignancy at surgical excision of only 1.5% to DCIS and 0% to invasive cancer. 4
Other concordant benign pathologies without atypia have a similarly low upgrade rate of 4.3% to DCIS and 0% to invasive cancer. 4
Critical Clinical Pitfalls
Never dismiss architectural distortion without additional imaging evaluation. Spot compression views must be obtained to exclude summation artifact before providing reassurance. 5
Always perform targeted ultrasound even when mammographic findings seem straightforward, as the presence or absence of a sonographic correlate dramatically alters malignancy probability. 5, 1
Recognize that architectural distortion is a commonly missed sign of breast cancer and represents a frequent cause of false-negative screening mammograms, particularly in interval cancer cases. 6, 7
Do not rely on mammography alone for risk stratification, as ultrasound identifies additional lesions not visible on mammography in 63-69% of symptomatic cases. 5