Figure 2b.  (a) Low-power photomicrograph (original magnification, x40; hematoxylin-eosin stain) shows glandular structures of varying sizes (adenosis) with the smaller glands compressed by surrounding stromal sclerosis. (b) Low-power photomicrograph (original magnification, x40; immunoperoxidase stain with monoclonal antibody HHF-35) demonstrates a layer of cells immunoreactive for muscle actin around each of the small glands. The presence of these myoepithelial cells suggests a benign process (adenocarcinoma of the breast usually has no myoepithelium).