Mills Ch3 Breast

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SECTION II : Breast

A

B

FIGURE 3.3  The stroma is the predominant component of the nonlactating breast and consists of varying amounts of collagen and adipose tissue. A: Low-power view of breast with dense, fibrotic stroma. B: Low- power view of breast with predominantly fatty stroma.

The actual number of segments in the breast and their relationship to each other has long been a matter of debate. Most textbooks indicate that there are 15 to 20 ductal ori- fices on the nipple surface and suggest that this corresponds to the number of ductal systems, segments, or lobes in the breast (5,6,15,16). In contrast, a number of mammary duct

injection studies have suggested that there are only between 5 and 15 discrete breast ductal systems or segments in each breast. The discrepancy between the number of duc- tal orifices on the nipple and the actual number of breast segments or ductal systems may be explained by the fact that some of the orifices on the nipple represent openings of sebaceous glands or other nonductal tubular structures that do not contribute to the ductal-lobular anatomy of the breast. Another possibility is that some lactiferous ducts bifurcate immediately prior to entering the nipple or end blindly (16,17). The issue of anastomoses between ductal systems is also unresolved. One study indicated that, while ductal systems may lie in close proximity to one another and even intertwine within a particular quadrant, they do not interconnect (16). However, anastomoses between ductal systems have been reported by others (18).

FIGURE 3.4  Ductogram (galactogram). Performed by injecting con- trast material into an orifice of a lactiferous duct at the nipple, a duc- togram demonstrates the complex ramifications of a single mammary ductal system (also known as a segment or lobe).

FIGURE 3.5  Microanatomy of normal adult female breast tissue show- ing extralobular ducts, terminal ducts, and lobules, the latter composed of groups of small glandular structures, the acini.