Breast calcifications

Breast calcifications can arise from a vast number of aetiologies. 

Epidemiology

They are extremely common and can be present in ~85% of mammograms ⁸. Their frequency increases with age. Up to 50% of breast cancers can be associated with calcification while 15-30% of calcifications biopsied for various reasons tend to be malignant in asymptomatic patients ¹⁰.

Pathology

Calcification can comprise of:

• calcium phosphate salt deposition: stains purple on routine H&E stain
• calcium oxalate salt deposition: can be difficult to visualise on H&E stain, requires the use of polarized light to assess birefringence

Classification

Breast microcalcifications can be grouped according to location, distribution, morphology or underlying aetiology. 

Location

• lobular calcification within breast tissue: well-defined, usually punctate and if multiple, spread throughout the breast; most of them have a small lucent centre; and tend to look the same with no pleomorphism; these may be bilateral
• intraductal calcification within breast tissue: these are either the calcifications of DCIS or casting calcifications in a duct
• milk of calcium within a breast cyst: the classic "tea cups" that show a level on the mediolateral view but a smudge on the CC view
• vascular calcification in breast tissue: when extensive they are easy to pick up; when they are just isolated in one vessel they can potentially be confused with DCIS; the vessel has two walls and in most cases a tram line can be visualised if both walls are calcified
• skin (dermal) calcification in/around breast tissue: they have a very fine lucent centre; they are seen in the skin line on the edge of the breast and are very small punctate calcifications in the skin pores
• suture calcification within breast tissue
• stromal calcification within breast tissue
• artifactual calcification from outside the breast

Distribution

• diffuse/scattered calcification: may be scattered calcifications or multiple similar appearing clusters of calcifications throughout the breast
• regional calcification: scattered in a larger volume (>2 cc) of breast tissue and not in the expected ductal distribution
• grouped calcification / grouped calcification: at least 5 calcifications occupying a small volume of tissue (<1 cc)within 1 cm from each other, in an area at most 2 cm in greatest dimension
• linear calcification: calcifications arrayed in a line suggestive of deposition along ducts
• segmental calcification: calcium deposits in ducts and branches of a segment or lobe

Morphology

• microcalcifications within breast
  • pleomorphic microcalcifications within breast: different shapes, sizes and densities are potentially alarming; the calcifications of DCIS are different shapes, sizes and densities. They are wild and crazy and have been described as "X's Y's and Z's" which in many cases is quite true
  • rounded microcalcification within breast
  • punctate microcalcification within breast
  • amorphous calcification within breast
• macrocalcifications within breast
  • coarse macrocalcifications within breast
  • popcorn calcification within breast - involution of a fibroadenoma
  • egg shell/rim calcification within breast

Underlying aetiology

• from fat necrosis
• from malignancy
  • intraductal calcification
  • psammomatous calcification from mucin producing tumours
• from fibrocystic change
  • liponecrosis microcystica
  • from an oil cyst
• from secretary calcification: plasma cell mastitis
• from a degenerating fibroadenoma
• from an underlying metabolic abnormality
  • tumoral calcification within breast
  • dystrophic calcification within the breast
• from parasitic infestations
  • loaisis of the breast
  • trichinosis of the breast

Note on segmental distribution

If microcalcifications are distributed in a segment of the breast they deserve special attention. Calcifications running from the nipple posteriorly in a breast segment is a potentially sinister sign and the possibility of DCIS involving a whole breast segment should be kept in mind. See case 18966.

Why breast calcifications are significant

There are two main reasons why calcifications are potentially significant:

1. A percentage of breast malignancies present as microcalcifications before they present as a mass. The prime example is DCIS, a non-obligate precursor of infiltrating ductal carcinoma. In the days before senology was accepted as a diagnostic technique, the diagnosis of breast cancer was made after the patient presented with a mass or metastases or post mortem. Depending on which reference you use, the incidence of DCIS in large screening series is around 30%. Coincidentally, this is also the rate of decreased mortality attributed to screening in the literature.

2. The second reason breast calcifications are important is the science involved to be able to diagnose and manage and distinguish significant microcalcifications from insignificant ones. The ability to diagnose and appropriately manage the significant microcalcifications and differentiate them from innocuous findings is part of the art of breast imaging.

The ability to diagnose a malignancy early implies that the disease is potentially curable with less chance of metastatic disease and with potentially less invasive surgery. Coupled with improvements in therapy, this shows why regular screening mammography results in more people surviving.

A suggested initial approach

For the novice, the interpretation and approach to breast calcifications can be intimidating. An approach is to use reference 12 below. The book is readable in a weekend and gives a morphological atlas as well as differential diagnosis to the most commonly encountered calcifications in the breast. The illustrations are good and representative and serve as a good guide. The breast section of this site contains a wide variety of cases to review.

See also

• suspicious breast calcifications