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INTRODUCTION

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Breast disease in women encompasses a spectrum of benign and malignant disorders, which present most commonly as breast pain, nipple discharge, or palpable mass. The specific causes of these symptoms vary with patient age. Benign disorders predominate in young premenopausal women, whereas malignancy rates increase with advancing age. Evaluation of breast disorders usually requires the combination of a careful history, physical examination, imaging, and, when indicated, biopsy.

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ANATOMY

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Ductal System

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The glandular portion of the breast is composed of 12 to 15 independent ductal systems that each drain approximately 40 lobules (Fig. 12-1). Each lobule consists of 10 to 100 milk-producing acini that empty into small terminal ducts (Parks, 1959). Terminal ducts drain into larger collecting ducts that merge into even larger ducts, which exhibit a saccular dilation just below the nipple called a lactiferous sinus (Fig. 12-2).

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FIGURE 12-1

A. Ductal anatomy of the breast. (Reproduced with permission from Going JJ, Moffat DF: Escaping from Flatland: clinical and biological aspects of human mammary duct anatomy in three dimensions, J Pathology 2004 May;203(1):538–544.) B. Terminal duct—acinar structure from a fine-needle aspiration biopsy. C. Histology of a normal breast lobule. The terminal duct lobular units are surrounded by loosely cellular intralobular stroma, which consists of dense fibrous tissue admixed with adipocytes.

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FIGURE 12-2

Breast anatomy. (Reproduced with permission from Seeley RR, Stephens TD, Tate P: Anatomy and Physiology, 7th ed. New York: McGraw-Hill; 2006.)

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In general, only six to eight openings are visible on the nipple surface. These drain the dominant ductal systems, which account for approximately 80 percent of the breast’s glandular volume (Going, 2004). Minor ducts either terminate just below the nipple surface or open on the areola near the base of the nipple. The areola itself contains numerous lubricating sebaceous glands, called Montgomery glands, which are often visible as punctate prominences.

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In addition to epithelial structures, the breast is composed of varying proportions of collagenous stroma and fat. The distribution and abundance of these stromal components accounts for a breast’s consistency when palpated and for its imaging characteristics.

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Lymphatic Drainage

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Afferent lymphatic drainage of the breast is provided by dermal, subdermal, interlobar, and prepectoral systems (Fig. 12-3)(Grant, 1953). Each of these may be viewed as a lattice of valveless channels that interconnect with every other system and that ultimately drain into one or two axillary lymph nodes (the sentinel nodes). Because all of these systems are interconnected, the breast drains as a unit, and injection of colloidal dyes in any part of the breast at any level will result in accumulation of dye in ...

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