Rosen's Breast Pathology, 4e

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Ductal Carcinoma In Situ

FIG. 11.11.  DCIS, flat (“clinging”) micropapillary type. A: The papillary structures in this cystically dilated duct contain fractured calcifications of the ossifying type typically associated with colum- nar cell lesions. B: Carcinoma cells with pleomorphic nuclei and a disorderly distribution line the duct and overlie the calcification. C: The flat carcinomatous epithelium displays apical apocrine- type cytoplasmic “snouts.” D–F: Other examples of flat, “clinging” DCIS.

(see Chapter 9). Squamous metaplasia can be encountered in micropapillary DCIS (Fig. 11.17). Clear cell micropapil- lary DCIS is uncommon (Fig. 11.18). A minority of micropapillary carcinomas are composed of cells with intermediate- or high- (poorly differentiated) grade cytologic characteristics (Figs. 11.9, 11.16, and 11.19).

Cells forming this type of carcinoma differ from those in the conventional micropapillary lesions by being larger, with more abundant cytoplasm. Nuclei are also correspond- ingly larger, and nucleoli may be apparent. Mitoses can be found in this epithelium, and the cells often have a distinctly apocrine appearance. The cytologically high-grade form of