Architectural distortion in breast imaging refers to an unusual pattern of breast tissue where the normal architecture appears pulled in or disrupted without a clear, defined mass. This alteration indicates an area requiring further investigation in breast health assessment.
Understanding Architectural Distortion
Architectural distortion manifests on imaging as a disruption of the breast’s normal tissue pattern, often appearing as fine lines or spicules radiating from a central point, or as focal retraction and distortion at the edge of the breast tissue. It can also involve the blurring of normal tissue planes. This finding can be detected through various imaging modalities, including mammography (particularly digital breast tomosynthesis or 3D mammography), ultrasound, and magnetic resonance imaging (MRI). Digital breast tomosynthesis has improved the detection of these subtle distortions compared to traditional 2D mammography.
This appearance raises concern because it can indicate underlying changes within the breast tissue. The distortion occurs due to the infiltration of cells, such as cancer cells, into the surrounding tissue, which pulls and alters the breast’s normal structure. Architectural distortion is recognized as the third most common mammographic finding of non-palpable breast cancers, making its identification important for early detection.
Assessing the Likelihood of Cancer
The probability of architectural distortion representing cancer varies, with studies reporting a positive predictive value (PPV) for malignancy ranging from 10% to over 50% when detected by digital breast tomosynthesis. For architectural distortion that persists on mammographic imaging, the PPV for malignancy has been reported to be as high as 74.5%. Invasive ductal carcinoma and invasive lobular carcinoma are common types of breast cancer that can present as architectural distortion.
Several factors influence the likelihood of architectural distortion being cancerous. The presence of other associated findings, such as a distinct mass or calcifications, increases the suspicion of malignancy. If an architectural distortion also has a corresponding finding on ultrasound, the likelihood of it being malignant can be significantly higher, with some reports indicating nearly a threefold increased risk (82.9% with a sonographic correlate versus 27.9% without). Architectural distortion detected during a diagnostic mammogram is also more likely to be malignant (83.1%) compared to findings on a screening mammogram (67.0%). Radiologists often categorize architectural distortion as BI-RADS 4 (suspicious for malignancy) or BI-RADS 5 (highly suggestive of malignancy), with a higher BI-RADS category correlating with an increased chance of malignancy.
Diagnostic Pathways Following Detection
Upon detection of architectural distortion, further diagnostic imaging is typically recommended to gain a clearer understanding of the finding. This often includes additional mammographic views, such as spot compression and magnification views, to better visualize the area. Targeted ultrasound of the suspicious area is a common next step, providing a real-time assessment and sometimes identifying a correlating lesion that was not clearly seen on mammography. Breast MRI may also be utilized, particularly if ultrasound does not identify a clear correlate or if further evaluation is needed due to patient risk factors.
If the architectural distortion persists or remains suspicious after these additional imaging studies, a biopsy is usually recommended to obtain a definitive diagnosis. Common biopsy procedures include core needle biopsy, which removes small tissue samples for microscopic examination. In cases where the distortion is not visible on ultrasound, stereotactic or tomosynthesis-guided biopsy may be performed, using imaging guidance to precisely target the area. Surgical excisional biopsy, which removes the entire suspicious area, might be considered in certain situations, especially if prior less invasive biopsies are inconclusive or if a high-risk benign lesion is found.
Non-Cancerous Causes and Outcomes
Architectural distortion is not exclusively indicative of cancer; it can also be caused by several benign conditions. One common benign cause is a radial scar, also known as a complex sclerosing lesion, which is a benign growth that can mimic malignancy on imaging due to its spiculated appearance. These lesions are not related to prior trauma or surgery but are often discovered incidentally.
Other non-cancerous causes include scarring from previous breast surgeries (such as biopsies, lumpectomies, or breast reduction procedures), fat necrosis (a benign condition resulting from trauma or other insults to breast fat), fibrocystic changes, inflammation, and sclerosing adenosis. If a biopsy reveals a benign cause for the architectural distortion, active treatment for cancer is not necessary, though ongoing surveillance may be recommended depending on the specific benign diagnosis.