Breast Diseases

4 Breast Diseases



Anatomy of the Breast



image

Mammary Gland



Basic Structure



• Adipose tissue and lactiferous glands lie between superficial and deep layers of superficial thoracic fascia.

• Cooper’s (suspensory) ligaments: partitions of fibrous connective tissue running from the deep fascia over the pectoralis major, external intercostals, and serratus anterior, through the breast parenchyma, to the dermis and superficial fascia

• Cooper’s ligaments form septa around glandular clusters and fat.

• Lactiferous ducts communicate with openings on nipple and areola.

• Accessory glands in areola: Montgomery’s tubercles

• Nipple contains skin, connective tissue, sebaceous glands, smooth muscle, vessels, and ducts.


Endocrinology



• Estrogen (e.g., in pregnancy) and tissue-based estrogen receptors control glandular proliferation and secretory states in concert with progesterone and other hormones and growth factors.

• Cyclic increases in estrogen level cause swelling and promote glandular growth.

• Cyclic increases in progesterone increase glandular maturation; decreases are associated with menses.


Sensory Innervation



• Cutaneous and deep, lateral cutaneous branches of T2-T6

• Nipple, T4, anterior and anterolateral (cutaneous) branches of 4th intercostal nerves

• Nerve compression by surrounding muscle can cause pain (e.g., Tietze’s syndrome, T4).


Development and Embryology



• Ducts and alveoli of glands are formed from invaginating ectoderm.

• Supporting connective tissue, blood vessels, and lymphatics are formed from mesenchyme.

• Embryonic mammary ridges extend from axilla to inguinal region; all but the most superior usually regress.

• Accessory or supernumerary nipples may be found along “this milk line.”

• Accessory axillary breast tissue is a developmental anomaly.


Vessels and Lymphatics



image

Vessels and Lymphatics of Breast



Arterial Supply



• Medial: internal thoracic (mammary) artery, branch of subclavian (first division)

• Superior: supreme thoracic artery, branch of axillary (first division)

• Lateral: thoracoacromial, lateral thoracic, circumflex scapular, subscapular, and thoracodorsal branches of the axillary artery (second and third divisions)

• Inferolateral: contributions from lateral (perforating) branches of intercostal arteries


Venous Drainage



• Drainage toward the axilla and axillary vein via named branches, including supreme thoracic, thoracoacromial, lateral thoracic, circumflex scapular, subscapular, and thoracodorsal

• Deep and medial drainage, including chest wall
image Anteriorly to intercostal veins and into the internal thoracic (mammary) veins

image Posteriorly through posterior intercostal veins into the azygos and hemiazygos vein systems


Lymphatic Drainage



• Drainage is extensive and multidirectional.

• Main flow is lateral, to axillary nodes.
image Level I : lateral and inferior to the lower border of the pectoralis minor

image Level II: deep, posterior to the pectoralis minor, including Rotter’s nodes between the pectoralis muscles

image Level III: above or medial to the upper border of the pectoralis major, including subclavicular and supraclavicular nodes

• Deep flow is along internal thoracic (mammary) vessel pathways to parasternal nodes, draining toward subclavian, supraclavicular, and deep cervical nodes.

• Metastasis spreads through groups of nodes in an unpredictable manner.

• Location of sentinel node (nearest, with metastasis) in axilla depends on the patient’s specific drainage pattern from the tumor site.

• Dye, tracer, or biopsy can miss real sentinel nodes (false negatives).


Clinical Correlates



Diagnostic Procedures



• X-ray mammography is the gold standard.
image ~90% sensitivity and specificity, overall

image Sensitivity low in young women due to greater density of parenchymal tissue

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Aug 12, 2016 | Posted by in ANATOMY | Comments Off on Breast Diseases

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