Tiny round punctate calcifications (< 0.5 mm) in a group (five or more calcifications per cubic centimeter) can be considered probably benign if no prior mammograms are available to confirm stability and if there is no know ipsilateral breast cancer. If punctate calcifications are in a linear or segmental distribution, they are suspicious and biopsy is indicated [7].

The morphology of the calcifications related to DCIS is usually fine linear or fine linear branching, fine pleomorphic, amorphous, or coarse heterogeneous. Fine linear and fine linear branching calcifications have the highest risk of malignancy with a positive predictive value (PPV) of 70 % (Fig. 3.3). The PPV of fine pleomorphic, amorphous, and coarse heterogeneous is 29, 21, and 13 %, respectively (Table 3.1) [8–12]. The fine linear and fine linear branching calcifications seen in DCIS are usually more irregular, thinner, and have a more discontinuous pattern than the benign, large, rod-like calcifications. Unlike the suspicious linear morphology, secretory calcifications may have lucent centers if the calcification is in the wall of a duct.

The distribution of calcifications in a segmental or linear distribution has the highest risk of malignancy, followed by grouped and regional (Table 3.2) [9, 11, 12]. Calcifications located in a line suggest malignant deposits in a duct and calcifications in a segmental distribution suggest deposits in ducts and their branches. Calcifications associated with DCIS can involve a large portion of the breast. However, diffuse, randomly distributed, punctate, and amorphous calcifications are usually benign and are usually bilateral .

Most mammographic calcifications are benign; however, those which are malignant are usually associated with DCIS. Stomper and colleagues reviewed malignant mammographic calcifications without an associated parenchymal lesion and found pure DCIS in 65 %, DCIS with a focus of invasion in 32 %, and invasive carcinoma alone in 4 % of the cases [13].

When DCIS presents as a parenchymal lesion, with or without associated calcifications, it can have the appearance of invasive cancer. The atypical mammographic features seen in 20 % of DCIS lesions include circumscribed masses, spiculated and irregular masses, focal asymmetries, and architectural distortion. The masses may be single or multiple.

If suspicious calcifications are associated with an asymmetry or mass, there is a greater probability that the calcifications are related to invasive carcinoma or DCIS with invasive carcinoma rather than DCIS alone (Fig. 3.4). Farshid et al.’s study demonstrated that when DCIS formed parenchymal lesions without radiographically visible calcifications, it was more frequently low grade and with calcifications more frequently high grade. Periductal fibrosis and chronic inflammation resulted in the parenchymal finding. The majority of the discrete masses had a papillary component (Fig. 3.5) [4] .

Many studies have attempted to correlate the pathologic findings or grade with the mammographic findings of DCIS; however, a significant overlap has been found. The presence or absence of necrosis is the pathologic feature that has the most correlation with the mammographic appearance of DCIS. Calcifications associated with necrosis are more likely to be in a segmental or linear distribution than calcifications in DCIS without necrosis [14]. Barreau et al. found a relationship between the extent of the calcification seen mammographically and the grade of DCIS, with grade 3 being more extensive.

The Digital Mammographic Imaging Screening Trial (DMIST) proved digital mammography is as efficacious as film screen mammography [15]. Digital mammography has been shown to be of better and more consistent quality compared to film screen mammography, with fewer artifacts and similar dose levels [16, 17]. There has also been a higher detection rate of breast calcifications found with digital mammography compared to film screen mammography [18, 19]. With mammographic calcifications commonly being the manifestation of DCIS [20], the transition from film screen to digital mammography has demonstrated an increase in the diagnosis of DCIS [18–21]. There is criticism that the higher rates of calcifications detected can represent overdiagnosis. This criticism is based on the belief that digital screening increased the detection of DCIS that would never have presented clinically. A variety of factors including nuclear grade and the presence of comedo necrosis have been associated with the risk of DCIS progressing to invasive cancer. The higher-grade lesions have a greater risk of recurrence and tend to progress more rapidly to invasive carcinoma, although all grades of DCIS have the potential of becoming invasive (Fig. 3.6). Studies have shown that the higher DCIS detection rates are related to higher detection rates of intermediate and high-grade DCIS lesions, not low grade. In the study by Weigel and colleagues, of the 1074 screen detected cancers, 17.2 % were low grade, 37.3 % were intermediate grade, and 40.3 % were high grade [22] .

All suspicious calcifications on the mammogram should be identified because the extent of the visible DCIS can affect whether breast conservation therapy (BCT) or mastectomy is recommended. It is crucial to obtain prior mammograms for comparison whenever possible, to avoid recommending removal of stable, benign calcifications. Many calcifications that would be considered suspicious if new would have a benign assessment if stability could be confirmed.

When DCIS is related to Paget’s disease, the mammogram may demonstrate subareolar or diffuse calcifications, a mass or masses, as well as skin thickening or nipple retraction. If nipple or subareolar findings are present on a mammogram, the nipple should be inspected clinically for signs of the disease. When clinical findings raise the possibility of Paget’s disease, a mammogram should be obtained to look for an underlying malignancy, although the mammogram may be normal [23] .