The mammary border or nipple line appears in the sixth week of embryo development and is identified in the form of an ectodermal thickening from the armpit to the groin. The caudal two-thirds of this line show regression and their abnormal persistence is often confused with nevi or moles. Aberrant breast tissue in the armpit or at any point outside the aforementioned border manifests itself during the hormonal stimulation of pregnancy and its treatment is surgical removal.

The decrease in the mother's estrogen levels after birth stimulates the production of prolactin by the newborn with colostrum (witch's milk) secretion for several days in boys and girls.

Except for mild hypertrophy during the neonatal period and puberty, the male breast area shows little change throughout life. The prepubertal "mound" of the woman arises between the ages of 11 and 15. There is lobe formation after the first ovulation. The sinus of the young adult extends from the second to the sixth ribs and from the sternum to the anterior axillary line. E1 glandular tissue has a circular shape, except for Spence's tail, which reaches the armpit. Cooper's fibrous ligaments suspend glandular tissue from the anterior superficial aponeurosis under the skin. The subareolar area and nipple contain smooth muscle that contracts with tactile stimulation.

The lymph nodes in the area of the inner and axillary mammary are responsible for the drainage of the breast.

Axillary levels: I, outside the pectoralis minor; II, below the pectoralis minor; III, inside the pectoralis minor. The Rotter ganglia constitute a group that is located between the pectoralis major and minor muscles. Drainage is done from the bottom up and eventually to supraclavicular ganglia, and then through the thoracic duct to the venous system. The average number of lymph nodes recorded in operations is five internal mammary nodes and 20 axillary nodes (levels I, II and III).

Physiology

The development and function of the breast is initiated by various hormones. Estrogen is known to stimulate the formation of the mammary ducts. Progesterone begins the development of breast lobules and the differentiation of epithelial cells. Prolactin stimulates lactogenesis. Cyclic changes: the volume increases almost 50% after the eighth day of the menstrual cycle. Vascular congestion and lobular proliferation show regression with menstruation.

• Pregnancy and lactation: the lobular alveolar ducts proliferate after the regression that occurs when the breastfeeding phase ceases. The nipple and areola are darkened and the Montgomery glands of the areola protrude. Appears nestries.
• Menopause: the lobules involute and fat replaces the parenchyma.
• Aberrations: Asymmetrical development or virginal hypertrophy in young girls can be surgically corrected after maturity. Gynecomastia in pubertal males is corrected if there is no reversal or hormonal abnormalities.

Physical examination

• Inspection: The operator can more easily detect asymmetry, skin depressions, edema and nipple inversion if the woman is seated, with her hands on the hip and then raises them above the head.
• Palpation: With the patient seated and then erect, the operator explores the supraclavicular area and axillary fossa, and also Spence's tail and central breast tissue. The entire breast is checked again with the woman lying on her back and with her arms above her head. Important features of a tumor or node are its size, shape, mobility, and fixation.
• Studies:
  • Mammography: The American Cancer Society recommends "basal" mammograms between ages 35 and 40, then every two years between ages 40 and 50, and every year after age 50. If there is a family history, the first mammogram must be obtained at age 35 and an annual plaque after age 40. The mammogram assesses stromal changes, in contrast to the fatty areas of the breast, so it is more accurate in the fatty breasts of postmenopausal than in the glandular sinuses of premenopausal breasts. Suspicious patterns of carcinoma include skin thickening, stromal densities with "radiated" invasion of the parenchyma, and microcalcifications (debris expelled into the ducts by rapidly dividing cells, especially common in intracanalicular cancers). Mammography is especially useful in the exploration of non-palpable lesions, to study the contralateral sinus in women with cancer, and in the follow-up of the ipsolateral breast after a conservative treatment of Cancer. The frequency of false positive results is 11% and that of false negatives 6%. Prospective studies demonstrated earlier detection of cancer and improved survival through mammography identification. Xeroradiography is similar to mammography but positive rather than negative images and increases radiation exposure, which is why it is not recommended. Thermography: tumors or infections generate "hot spots", but they are an unreliable method.
  • Ultrasonography: cysts are distinguished from solid lesions by ultrasound, but with this method microcalcifications are not detected. Needle aspiration is a simpler and less expensive technique for detecting cysts. Its main indication is to study suspicious lesions not palpable in mammography.
  • Other methods: Computer tomography and nuclear magnetic resonance imaging are still in the experimental phase in the detection of breast cancer.
  • Ductography: consists of the injection of radiopaque contrast into a milk duct. It is indicated by nipple secretions, particularly if they are bloody.