Amorphous calcifications (breast)

Amorphous calcifications, previously known as indistinct calcifications, are a morphological descriptor for breast calcifications that are small and/or hazy such that no clearly defined shape/form can be ascribed. 

Pathology

Many benign and malignant conditions may be seen in association with these calcifications ¹.

• benign: ~60%
  • fibrocystic change
  • fibroadenoma
  • sclerosing adenosis
  • papilloma
• high risk lesions: ~20%
  • atypical ductal hyperplasia (ADH)
  • atypical lobular hyperplasia (ALH)
  • lobular carcinoma in situ (LCIS)
• malignant: ~20% ^1-2
  • low grade ductal carcinoma in situ (DCIS)
  • invasive ductal carcinoma ~10%: usually has an accompanying mass

Radiographic features

Magnification views as part of a diagnostic mammographic evaluation are required to fully assess these calcifications.

Amorphous calcifications are small (80-200 micrometer in diameter) and/or hazy/faint, such that a more specific morphologic descriptor cannot be assigned.

Radiology report

Given the 20% positive predictive value of malignancy, most amorphous calcifications are assessed as BI-RADS 4B (suspicious, warranting biopsy) ⁵. That assessment particularly applies to amorphous calcifications with a grouped, linear, or segmental distribution. However, bilateral diffuse amorphous calcifications may be assessed as BI-RADS 2 (benign). If long-term (2-3 year) stability has been demonstrated, a BI-RADS 2 assessment would also be appropriate.

If the interpreting radiologist has sufficient personal experience with this finding to suggest <2% risk of malignancy to justify a watchful waiting approach, a BI-RADS 3 assessment may be entertained, but this approach is not supported by the literature ⁵.