Architectural distortion in breast imaging refers to a change in the normal tissue pattern. While it always warrants further investigation, this finding is not always indicative of cancer, prompting medical evaluation to determine its underlying cause.
Understanding Architectural Distortion
Architectural distortion is characterized by a “pulling in” or “star-like” appearance of breast tissue without a clear, discernible mass. It often appears as thin lines or spicules radiating from a central point, or as focal retraction or distortion at the edge of the breast tissue. This visual anomaly is a significant finding for radiologists.
This subtle finding can be detected during various breast imaging procedures, including 2D mammography and 3D mammography (tomosynthesis). Tomosynthesis has improved the detection of architectural distortion by allowing radiologists to view the breast in thin, sequential sections, which helps differentiate true distortions from overlapping normal breast tissue.
Frequency of Cancer Diagnosis
The likelihood of architectural distortion representing cancer varies across studies. While it is a significant finding, it is more often benign than malignant. Malignancy rates reported in studies range from approximately 10% to over 70%.
Several factors influence the probability of malignancy when architectural distortion is detected. Architectural distortion found during diagnostic mammography is more likely to be malignant than that found on screening mammography. If the architectural distortion has a correlating finding on ultrasound, the risk of malignancy is significantly higher compared to cases without a sonographic correlate.
Investigating Architectural Distortion
When architectural distortion is identified, additional imaging is typically recommended to further evaluate the finding. This often includes diagnostic mammography, which may involve specialized views like spot compression, and breast ultrasound. Magnetic Resonance Imaging (MRI) may also be used, particularly in cases where no other findings are seen on mammogram or ultrasound.
A biopsy is frequently performed to determine the underlying cause and differentiate between benign and malignant findings. This may involve stereotactic biopsy, guided by mammography, or ultrasound-guided biopsy, depending on the visibility of the distortion on each modality. A multidisciplinary approach, involving radiologists, surgeons, and pathologists, is often employed to ensure comprehensive evaluation and appropriate patient management.
Causes of Architectural Distortion
Architectural distortion can stem from both benign and malignant conditions. Benign causes include scarring from prior surgeries or biopsies, which can pull and distort the surrounding breast tissue. Radial scars, also known as complex sclerosing lesions, are another common benign cause characterized by a central fibrous core with radiating structures. Fat necrosis, resulting from injury or inflammation of fatty breast tissue, can also lead to architectural distortion as the body attempts to repair the damaged area with fibrosis. Sclerosing adenosis, a condition where there is an overgrowth of glandular tissue with associated fibrosis, can also manifest as architectural distortion.
Malignant causes include various types of breast cancer. Invasive ductal carcinoma, the most common type, frequently presents with architectural distortion due to its infiltrative growth pattern. Invasive lobular carcinoma is another significant cause, often appearing as subtle architectural distortion without a distinct mass due to its diffuse growth. Ductal carcinoma in situ (DCIS) can also present with architectural distortion, though less commonly, often linked to associated sclerosing adenosis or fibrous changes.