Mills Ch3 Breast

77

CHAPTER 3:  Breast

TABLE 3.2 Histologic Changes in Lobules During the Menstrual Cycle Menstrual Cycle Phase Epithelium

Acinar Lumina

Intralobular Stroma

Largely closed and inapparent

Dense, cellular, with plump fibroblasts

Early follicular

Cells: single cell type (small, polygonal cells with pale eosinophilic cells); myoepithelial cells inconspicuous

Orientation: poor Secretion: none Mitoses/apoptosis: rare

Well-defined

Less cellular and more collagenized than in early luteal phase

Late follicular

Cells: three cell types, including luminal basophilic cells, intermediate pale cells (as seen in early follicular phase), and myoepithelial cells with clear cytoplasm Orientation: radial around lumen Secretion: none Mitoses/apoptosis: rare Cells: three cell types, including luminal basophilic cells with minimal apical snouting, intermediate pale cells, and myoepithelial cells with prominent cytoplasmic vacuolization and ballooning Orientation: radial around lumen Secretion: slight Mitoses/apoptosis: rare Cells: three cell types, including luminal basophilic cells with prominent apical snouting, intermediate pale cells and myoepithelial cells with prominent cytoplasmic vacuolization Orientation: radial around lumen Secretion: active apocrine secretion from luminal cells Mitoses/apoptosis: frequent (peak of mitotic activity) Cells: two cell types, including luminal basophilic cells with scant cytoplasm and less apical snouting than in late luteal phase, and myoepithelial cells with extensive cytoplasmic vacuolization Orientation: radial around lumen Secretion: resorbing Mitoses/apoptosis: rare

Loose

Open, enlarged compared to follicular phase, with slight secretion

Early luteal

Open, with secretion

Loose, edematous, congested blood vessels

Late luteal

Distended with secretion Dense, cellular

Menstrual

Adapted from McCarty KS, Nath M. Breast. In: Sternberg SS, ed. Histology for Pathologists . Philadelphia, PA: Lippincott-Raven; 1997: 71–82.

Both the nipple and areola are covered by keratiniz- ing, stratified squamous epithelium, and this extends for a short distance into the terminal portions of the lactifer- ous ducts. The epidermis of the nipple–areola complex may contain occasional clear cells that are cytologically benign and that must not be confused with Paget cells (Fig. 3.13) (55,56). Some of these cells represent clear keratinocytes, whereas others are thought to be derived from epidermally located mammary ductal epithelium (Toker cells) (56). The proximal ramifications of the mammary ductal sys- tem that are present in the dermis of the nipple typically have a pleated or serrated contour (Fig. 3.14). These ducts are surrounded by a stroma rich in circular and longitu- dinal smooth muscle bundles, collagen, and elastic fibers (Fig. 3.15). Occasionally, lobules may be seen in the nipple (57). Simple mammary ducts are also present throughout the dermis of the areola, even at its periphery, and these

FIGURE 3.13  Clear cells in nipple epidermis. In some cells, the clear- ing is extreme, with formation of large intracytoplasmic vacuoles. These cells should not be mistaken for the cells of Paget disease.