Dystrophic calcifications occur in surgical beds of both benign and malignant disease and in areas of trauma. They are common in lumpectomy beds after radiation therapy. Dystro- phic calcifications are coarse, sheetlike, and are occasionally accompanied by fat necrosis with lucent centers (Fig. 3.32 and Fig. e3.3). Unlike rim calcifications, dystrophic calcifications do not always have central lucent fat on mammograms. A his- tory of previous surgical biopsy or trauma, when correlated with a surgical scar or area of trauma, should reveal that the calcifications are dystrophic.
On tomosynthesis, the lucent center may be more clearly visu- alized than on conventional mammograms (see Fig. 3.32), but the margin of the dense calcification may be accentuated by a
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FIG. 3.27 Typically benign: round calcification, examples of primarily round calcifications (0.5–1 mm in size).
Dense and sharply marginated round calcifications are scattered in the breast and vary in size (A and B). Some calcifications show a rim appearance (A and B; arrows) that may represent calcified dilated ductal structures or oil cysts that are clearly uncharacteristic of malignancy.
Acinus
Round calcifications FIG. 3.26 Schematic of round calcifications. Calcifications in benign disease form in the acini or lobules of the duct, so they look round.
BOX 3.10 Methods to Identify Posttraumatic Dystrophic Calcifications
Metallic scar marker to show the biopsy site
Look for fat on old films in the region where calcifications now project
Look at old films for biopsied lesions; correlate the scar site with the current location of calcifications
BOX 3.9 Typical Size of Round and Punctate Calcification
Round 0.5–1 mm Punctate <0.5 mm
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2D Tomo-synthesized 2D Tomo slice
FIG. E3.3 Typically benign: dystrophic calcification. Conventional 2D mammogram versus tomosynthesis. (A) Conventional 2D mam- mogram. (B) Tomosynthesis-synthesized 2D mammogram. (C) Tomosynthesis 1-mm slice. After lumpectomy and radiation therapy, dystrophic calcification forms as a sheetlike calcification with radiolucent center. Note the shadow artifact surrounding dense calcification on tomosynthesis-synthesized 2D view (B) and tomosynthesis slice (C).
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FIG. E3.2 Typically benign: round calcifications: examples of punctate calcifications (<0.5 mm in size) with varying pathologies. (A–B) Benign-appearing punctate calcifications in two different cases. In A, the calcifications were stable for several years and considered be- nign. However, in B, the calcifications were new or increasing, and biopsy showed fibrocystic change. (C) Atypical ductal hyperplasia.
Although round and punctate calcification belong to the typically benign group in BI-RADS, they can occur in high-risk lesions too, and are especially worrisome if they are new or increasing.
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FIG. 3.28 Typically benign: round calcifications, distribution. Bilateral craniocaudal views show round and punc- tate calcifications in bilateral and diffuse distribution suggesting their benign entity.
FIG. 3.29 Round calcifications on tomosynthesis. Tomosynthesis may be helpful in distinguishing intraparenchy- mal calcifications from skin calcifications and to determine whether they are grouped or scattered when scrolling through the tomosynthesis data asset. Note the typical shadow artifacts (arrows) above and below a fairly large round calcification.
tomosynthesis artifact, depending on the vendor (see Fig. e3.3).
To determine whether suspect dystrophic calcifications are from scarring, some facilities place a radiopaque linear scar marker directly on the patient’s skin scar to see if it correlates with apparent postbiopsy scarring on the mammogram (Box 3.10).
Calcifying sutures or benign fat necrosis usually develops 2 years or later after surgery and radiation therapy, with the exception of those forming in accelerated partial breast irradia- tion (APBI) or intraoperative radiation therapy (IORT), which can form as early as 6 months after radiation. Dystrophic calcifi- cations in postradiation settings may be difficult to distinguish from cancer unless the classic sheetlike calcifications are seen or unless the calcifications calcify densely over time (Fig. 3.33).
Calcifications discovered in lumpectomy beds may also be calcifications in cancer missed at surgery or may be new. Com- paring the current study with the prebiopsy, immediate post- biopsy, and specimen mammograms will determine whether all of the calcifications were removed at surgery, were missed, or are new.
The differential diagnosis for new calcifications in a can- cer biopsy site is benign postbiopsy dystrophic calcification/
fat necrosis calcifications versus recurrent cancer. Radiation therapy fails at a rate of about 1% per year, resulting in fail- ure rates of about 5% at 5 years and 10% after 10 years. If the new calcifications are fine linear or fine-linear branching, fine pleomorphic, or increasing, biopsy should be performed
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FIG. 3.31 Typically benign: rim calcifications, examples of oil cysts. (A) A photographically magnified view of an oil cyst shows partial rim calcification around a radiolucent center, with plaquelike calcifications seen en face in the calcified oil cyst wall. (B) Lateromedial spot magnification mammogram in another patient shows a thin rim of calcification around a mostly radiolucent oil cyst.
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C
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FIG. 3.30 Typically benign: rim calcifications, examples of rim (formerly eggshell) calcifications. (A–C) Magni- fication views show typically benign small eggshell-like rim calcifications with a radiolucent center that are sur- rounded by relatively a dense calcific edge.
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A B C
2D Tomo-synthesized 2D Tomo slice
FIG. 3.32 Typically benign: dystrophic calcification, conventional 2D mammogram versus tomosynthesis. (A) Conventional 2D mammogram. (B) Tomosynthesis-synthesized 2D mammogram. (C) Tomosynthesis 1-mm slice.
Amorphous calcification surrounding a radiolucent center represents dystrophic calcification in the biopsy site as well as around an oil cyst after breast reduction surgery. The fatty radiolucent center (C; arrow) is more clearly visualized on tomosynthesis slice (C) than 2D (A) and tomosynthesis-synthesized 2D (B).
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FIG. 3.33 Typically benign: dystrophic calcification, time course. (A) Seven years after intraoperative radiation therapy (IORT). (B) Eight years after IORT in the same patient. Dystrophic calcification (arrows) developed and became denser over 1 year.
to exclude recurrent tumor. Because of the problem of recur- rent breast cancer in the cancer biopsy site, biopsy may be required for benign dystrophic calcifications that do not have a classic appearance.
A special type of calcification forms after IORT. These are typically tiny, round, and incredibly dense dystrophic calcifica- tions in the biopsy bed. They are so dense they almost look like metal shavings (Fig. 3.34). Unlike whole-breast radiation, which fractionates the dose over 6 weeks over the entire breast, IORT uses more intense, concentrated radiation for several minutes on only the biopsy site and a small margin of tissue around it dur- ing the operation. Because breast cancer recurrences most often occur in or around the biopsy site, the rationale for IORT is that it sterilizes only the biopsy bed and surrounding tissues in which the cancer may recur. The advantage of IORT is that it treats the biopsy bed without the collateral radiation of surrounding tis- sues from whole-breast radiation therapy. Good results with few cancer recurrences have been shown with IORT when synchro- nous ipsilateral cancers are excluded during patient selection.