Rosen's Breast Pathology, 4e

347

Ductal Carcinoma In Situ

medium-sized cells with high-grade round-to-oval nuclei with speckled chromatin. Such neoplastic cells are generally uniform, with centrally placed nuclei within which nucleoli are inconspicuous. So-called “flat epithelial atypia” (in most cases synonymous with atypical CCH) and low-grade DCIS of the breast have been shown to share highly homologous molecular and genomic profiles 118 ; however, such data can be interpreted as being reflective of the difficulty in distin- guishing between the two entities, morphologically as well as by molecular criteria, and the need to be conservative in the diagnosis of low-grade DCIS. Calcifications with distinctive crystalline, ossifying, and laminated appearances tend to occur in CCH, leading to mammographic detection. Patients with CCH may have tu- bular carcinoma, LCIS, and invasive lobular carcinoma, as well as micropapillary DCIS. Cribriform DCIS is a fenestrated epithelial proliferation in which microlumens are formed by neoplastic epithelium that bridges most or all of the duct lumen. Cribriform DCIS can be found at all levels of the main duct system frommajor ducts to terminal intralobular ductules. Extension into lobu- lar epithelium (so-called “lobular cancerization”) or into the main lactiferous ducts of the nipple is uncommon. ­Markedly dilated ducts with cribriform DCIS can be mistaken for

FIG. 11.13.  DCIS, micropapillary. Some epithelial fronds have delicate fibrovascular centers.

women 35 to 55 years of age. The lesions are typically mul- tifocal or multicentric and can be bilateral. Flat micropapil- lary (“clinging”) DCIS should be diagnosed whenever a flat epithelial proliferative process shows relatively small- to

A

B

FIG. 11.14.  DCIS, micropapillary. Intraductal micropapillary growth developing cribriform (A,B) and Roman bridge-like (C) structures.

C