FIGURE 2

Expression of ChA, ChB, GCDFP-15, and AR in different histotypes of NE breast cancers (solid cohesive, alveolar, and poorly differentiated types). Double immunostaining of a case of solid-cohesive carcinoma (immunoperoxidase and beta-galactosidase). ChA-positive NE cells are in brown, whereas apocrine-differentiated cells expressing GCDFP-15 are in blue (A). At higher magnification, the coexpression of ChA and GCDFP-15 in the same cells (arrows) is evident (B). Pure NE alveolar carcinoma featuring round alveolarlike structures, separated by scanty dense stroma, is formed by a homogeneous population of large clear cells, with faintly granular cytoplasm (C), positive for ChA (D). Poorly differentiated NE carcinoma shows clusters of cells, with moderate to abundant cytoplasm, nuclei with vesicular to finely granular chromatin, and high number of mitoses (E). Immunostaining for ChB shows an intense cytoplasmic granular staining (F). In a case of solid-cohesive spindle cell NE-apocrine carcinoma (G), the presence of specific mRNAs for ChA GCDFP-15 (nitroblue tetrazolium salt substrate) is demonstrated with in situ hybridization (H). The nuclei of the same tumor are intensely and diffusely positive for AR (I).