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Chapter 11

FIG. 11.1. DCIS, radiologic–pathologic correlation. A: Radiograph showing branching linear calcifica- tions found at biopsy to be in high-grade DCIS with necrosis (“comedo” type). Inset on left : typical “comedo” appearance on cut section. Inset on right : cross section of a duct with high-grade in situ carcinoma with central necrosis and calcification. B: Clustered, rounded punctate calcifications at the site of cribriformDCIS ( inset ). Inset images are from cases other than those shown in the radiographs.

in 12% of pure comedocarcinomas, and in 50% of cases with both patterns. 49 In patients who undergo mastectomy, ex- tension of DCIS to the nipple or subareolar region is more frequent with comedo than with cribriform–micropapillary DCIS. 49 The likelihood of detecting multifocal DCIS radio- logically and pathologically is related to the size of the lesion as determined by either procedure. 44,50 Multifocality is ap- preciably more frequent in lesions larger than 2.0 to 2.5 cm than in smaller foci of DCIS. Carlson et al. 48 reported that the mean size of multifocal DCIS (3.1 cm) was significantly greater than the size of nonmultifocal lesions (1.95 cm). The mammographic appearance of microcalcifications bears some relationship to the histologic type of the lesion, but, as noted by Stomper and Connolly, 51 “there is consider- able overlap, and the predominant histologic subtype can- not be predicted on the basis of the microcalcification type with a high degree of accuracy.” Predominantly linear calci- fications are found significantly more often in comedocar- cinomas than in cribriform, papillary, or solid types, which typically contain granular calcifications. 49,51 Nonetheless, 22% of linear calcifications were associated with noncom- edocarcinomas, and 47% of granular calcifications occurred in comedocarcinomas in one series. 51 The presence of exten- sive casting-type microcalcifications occupying more than one quadrant in a mammogram was associated with high- grade DCIS, multifocal invasive duct carcinoma, and axil- lary nodal metastases in 33% of 12 patients who had lymph nodes examined. 48 Image analysis of calcifications has had some success in discriminating between comedo and noncomedo DCIS. 52

Abnormal mammograms without calcifications are more likely to call attention to DCIS of the small cell type than the large cell type, regardless of the growth pattern (solid, crib- riform, or mixed) of the lesion. 53 Linear calcifications are a marker of necrosis, and granular calcifications are associated with DCIS without necrosis. 53 DCIS that overexpresses the human epidermal growth factor 2 ( HER2 ) oncogene is more likely to have calcifications detected by mammography than is a HER2 negative carcinoma. 54 Extent of mammographic calcifications, presence of either a radiographically or a clini- cally evident mass, and solid architectural type of DCIS have been demonstrated to be significantly associated with inva- sion on final excision. 55 Unusual mammographic presentations of DCIS occur when the lesion has a configuration that suggests a benign tumor or invasive carcinoma. These patterns, reflective of associated soft tissue masses, are found in less than 10% of mammographically detected DCIS. 45,56–59 In one series, 8% of DCIS were represented mammographically by stellate le- sions without calcifications, 59 and in another report, 3.6% of DCIS presented as stellate opacities. 56 Three were pure DCIS, and four proved to be DCIS arising in benign radial sclerosing lesions or “radial scars.” Microinvasion was found in only one case, despite the radiologic appearance suggest- ing invasive carcinoma in all instances. At the other end of the spectrum, DCIS may be harbored by radiologically cir- cumscribed lesions and appear to be benign. 57 In addition to carcinoma arising in a fibroadenoma, these are usually examples of solid papillary DCIS or nodular foci of comedo- carcinoma. Microinvasion may be present. 57