Anatomy of the Breast.
I've taken the answers from Moore's, Gray's Antomy and also Saddler's Embryology
1.1 What is the embryological explanation of accessory nipples?
The first indication of mammary glands is found in the form of a band-like thickening of the epidermis, the mammary line or mammary ridge. In a 7-week embryo, this line extends on each side of the body from the base of the forelimb to the region of the hindlimb. (Although the major part of the mammary line disappears shortly after it forms, a small portion in the thoracic region persists and penetrates the underlying mesenchyme . Here it forms 16 to 24 sprouts, which in turn give rise to small, solid buds. By the end of prenatal life, the epithelial sprouts are canalized and form the lactiferous ducts, and the buds form small ducts and alveoli of the gland. Initially, the lactiferous ducts open into a small epithelial pit. Shortly after birth, this pit is transformed into the nipple by proliferation of the underlying mesenchyme.
Polythelia is a condition where accessory nipples have formed due to the persistence of fragments of the mammary line. Accessory nipples may develop anywhere along the original mammary line, but usually appear in the axillary region.
Polymastia occurs when a remnant of the mammary line develops into a complete breast.
2.1 What is the arterial supply of the breast?
The arterial supply of the breast derives from the:
- Medial mammary branches of perforating branches and anterior intercostal branches of the internal thoracic artery, originating from the subclavian artery.
- Lateral thoracic and thoracoacromial arteries, branches of the axillary artery.
- Posterior intercostal arteries, branches of the thoracic aorta in the 2nd, 3rd, and 4th intercostal spaces.
3.1 How may Cooper’s ligaments be evident in breast carcinoma?
Interference with the lymphatic drainage by cancer may cause lymphedema (edema, excess fluid in the subcutaneous tissue), which in turn may result in deviation of the nipple and a thickened, leather-like appearance of the skin. Prominent or “puffy” skin between dimpled pores give it an orange-peel appearance (peau d'orange sign). Larger dimples (fingertip size or bigger) result from cancerous invasion of the glandular tissue and fibrosis (fibrous degeneration), which causes shortening or places traction on the suspensory ligaments. Subareolar breast cancer may cause retraction of the nipple by a similar mechanism involving the lactiferous ducts.
A well-developed, connective tissue stroma surrounds the ducts and lobules of the mammary gland. In certain regions, this condenses to form well-defined ligaments, the suspensory ligaments of breast, which are continuous with the dermis of the skin and support the breast. Carcinoma of the breast creates tension on these ligaments, causing pitting of the skin. Subcutaneous lymphatic obstruction and tumor growth pull on connective tissue ligaments in the breast resulting in;ll the appearance of an orange peel texture (peau d'orange) on the surface of the breast. Further subcutaneous spread can induce a rare manifestation of breast cancer that produces a hard, woody texture to the skin (cancer en cuirasse).
3.2 How may carcinoma spread via the lymphatics/veins/local invasion?
Breast cancer typically spreads by means of lymphatic vessels (lymphogenic metastasis), which carry cancer cells from the breast to the lymph nodes, chiefly those in the axilla. The cells lodge in the nodes, producing nests of tumor cells (metastases). Abundant communications among lymphatic pathways and among axillary, cervical, and parasternal nodes may also cause metastases from the breast to develop in the supraclavicular lymph nodes, the opposite breast, or the abdomen. Because most of lymphatic drainage of the breast is to the axillary lymph nodes (Fig. 1.24A), they are the most common site of metastasis from a breast cancer. Because most of lymphatic drainage of the breast is to the axillary lymph nodes (Fig. 1.24A), they are the most common site of metastasis from a breast cancer. Enlargement of these palpable nodes suggests the possibility of breast cancer and may be key to early detection. However, the absence of enlarged axillary lymph nodes is no guarantee that metastasis from a breast cancer has not occurred because the malignant cells may have passed to other nodes, such as the infraclavicular and supraclavicular lymph nodes.
Carcinoma of the breast usually arises in the upper outer quadrant and first spreads to the axillary nodes. However, medial breast lesions may drain through the chest wall to the nodes along the internal mammary artery. Thereafter, in both instances, the supraclavicular and infraclavicular nodes may be seeded. In some cases, the cancer cells seem to traverse the lymphatic channels within the immediately proximate nodes to be trapped in subsequent lymph nodes, producing so-calledskip metastases. The cells may traverse all of the lymph nodes ultimately to reach the vascular compartment via the thoracic duct.
4.1 How will you palpate the axillary lymph nodes?
Refer to PDF file.
5.1 Describe a normal mammogram
No thickening of the skin, no calcification and no dominant masses.
Radiographic examination of the breasts, mammography, is one of the techniques used to detect breast masses. A carcinoma appears as a large, jagged density in the mammogram. The skin is thickened over the tumor (upper two arrows in) and the nipple is depressed. Surgeons use mammography as a guide when removing breast tumors, cysts, and abscesses.
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