Breast architectural distortion

Breast architectural distortion is a descriptive term in breast imaging (mammography, ultrasound, and MRI) to indicate that the breast parenchyma is tethered or indented. The finding per se is is not a mass.

Pathology

Architectural distortion is often due to a desmoplastic reaction in which there is focal disruption of the normal breast tissue pattern. There are several features that can be considered as part of architectural distortion ³:

• contour abnormality
• trabecular thickening
• trabecular disorganisation

Aetiology

Many entities can cause architectural distortion ^1,4.In practice, the most common are surgery and malignancy. It is considered the third most common appearance of breast cancer ^1,6.

• primary causes
  • invasive breast cancer, including both invasive lobular carcinoma and invasive ductal carcinoma
  • ductal carcinoma in situ
  • radial scar/complex sclerosing lesion
  • fat necrosis
  • sclerosing adenosis
  • fibromatosis
• secondary causes 
  • postsurgical scars (most common)
  • trauma
  • infection

Radiographic features

Architectural distortion can be visually subtle. Compared to 2D mammography, digital breast tomosynthesis increases the sensitivity, confidence, and interobserver agreement in detection of architectural distortion ^7-10. Tomosynthesis also helps pinpoint the abnormality. Targeted ultrasound should then be performed to confirm the finding, but MRI is an alternative if no ultrasound correlate is found ⁹.

Mammography/US/MRI

Architectural distortion is characterized by a number of possible appearances ⁵:

• radiating thin straight lines or spiculations
• focal retraction, distortion, or straightening at the edge of the parenchyma
• blurring of normal tissue planes such as the fat-fibroglandular junction
• straightening or thickening of Cooper ligaments
• compression of tissue around a mass

Radiology report

Architectural distortion can be reported as a standalone finding or be associated with (adjacent to) another finding, such as asymmetry, calcifications, or mass. In most cases, architectural distortion is a suspicious finding (BI-RADS 4) ^8,9. The BI-RADS Atlas suggests that an ultrasound finding of architectural distortion thought to be due to postsurgical scar may be categorized as probably benign (BI-RADS 3), but there is sparse data supporting this approach ⁵.

History and etymology

In times before screening mammography became universally accepted, the diagnosis and surgery for breast pathology was a haphazard process at best. The diagnosis of carcinoma was invariably made once a tumour was clinically palpable to the clinician. Surgery was generally performed without preoperative imaging. The result was that women with benign breast changes would potentially end up with multiple surgeries to both breasts over the course of their lifetime. After mammography was implemented, it was often impossible to distinguish a postsurgical scar from the architectural distortion caused by the scirrhous reaction of a breast cancer. This is the reason why percutaneous needle biopsies are preferred in the eyes of the breast imager and why the demise of the blind open surgical biopsy was a happy day in the eyes of the breast imagerradiologist.