Mills Ch3 Breast

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SECTION II : Breast

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FIGURE 3.11  Intralobular and extralobular stroma. A: Low-power view of several lobules that are invested by loose, intralobular stroma. The interlobular stroma is composed primarily of dense collagen with admixed adipose tissue. B: Higher-power view contrasts loose intralobular stroma with more collagenized interlobular stroma.

some evidence to suggest the stage of involution is consis- tent across the breast and may provide an additional assess- ment of risk, the value of reporting the predominant lobular type in clinical practice remains to be determined (49). The lobules exhibit morphologic changes during the menstrual cycle, and these are seen in both the epithelial and stromal components (50–53). These changes are sum- marized in Table 3.2. While the changes that occur during the menstrual cycle are variable among lobules in the same breast, even among immediately adjacent lobules, a domi- nant morphologic pattern is typically present in each phase. However, these menstrual cycle–related changes are subtle when compared with the dramatic alterations seen during pregnancy and lactation and when compared with the men- strual cycle–related changes seen in the endometrium.

Occasionally, the TDLU epithelial cells show promi- nent clear cell change in the cytoplasm. This may be seen in both premenopausal and postmenopausal women and appears to be unrelated to pregnancy or exogenous hormone use (54). The nipple–areola complex is a circular area of skin that exhibits increased pigmentation and contains numerous sensory nerve endings. The nipple is placed centrally and is elevated above the surrounding areola. The tip of the nipple contains 15 to 20 orifices. However, as discussed earlier, the number of such openings may not correlate directly with the number of breast segments. In the nonlactating breast, these duct openings typically possess keratin plugs. The areola surface exhibits numerous small, rounded eleva- tions, the tubercles of Montgomery.

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FIGURE 3.12  Multinucleated stromal giant cells. A: Low-power view showing multinucleated giant cells scat- tered in the stroma. B: High-power view illustrates cytologic detail. These cells have a mesenchymal phenotype. Despite their worrisome histologic appearance, they have no known clinical significance.