Breast(mammary gland) By Dr Manah Chandra Changmai MBBS MS
Breast are present bilaterally in pectoral region They are modified sweat glands In male and immature female,breast are rudimentary After puberty,female breast are fully developed. Mammary gland
Vertically-2 nd to 6 th ribs
horizontally- from lateral border of sternum
To mid-axillary line along fourth rib.
Mammary bed: Rest upon following structures
Pectoralis major- In medial two thirds
Serratus anterior- lateral one third.
External oblique aponeurosis-
In infero-medial quadrant.
Female mammary gland
Retro-mammary space: Intervenes between base of the gland and the deep Fascia covering the mammary bed. Axillary tail of spence: -occasionally present -projection from the upper and outer quadrant of the gland. -enters the axilla through an opening in the axillary fascia(foramen of langer).
Features in the skin overlying the breast Nipple : -conical or cylindrical projection below the centre of the breast. -usually present at the fourth intercostal space. -pierced by 15-20 lactiferous ducts. -contains circular and longitudinally disposed smooth muscle.
Areola -pigmented circular area of the skin around the base of the nipple. -irreversibly darkened after first pregnancy. -outer margin contains modified sebaceous gland -these galnds enlarged during pregnancy and lactation(tubercles of montgomery)
Structure of the breast
Made up of three parts.
Interlobar fatty tissue.
Glandular tissue Lobes -15-20 lobes pyramidal in shape drained by a lactiferous duct. -All lobes converge towards the areola. -Near the areola each lactiferous duct dilates to form lactiferous sinus. -each duct drain open onto the nipple.. Lactiferous duct and Lobules -Each lactiferous duct drains a segmental segments of smaller duct. -segmental duct divides into small terminal duct -terminal duct gives rise to numerous sectretory pouches (alveoli) like cluster of grapes. -breast parenchyma drain by lactiferous duct is known as lobules. -the ducts possess myopeithelial cells.
From birth to pre-pubertal life : lactiferous ducts without alveoli At puberty : Ducts undergo branching,form solid spherical masses precusors of alveoli. In pregnancy : Further proliferation,epithelial growth of terminal duct increase in the alveoli per lobule. During lactation : Alveoli are distended by milk secretion,line by single layer of epitheium. After lactation : Glandular tissue returns to resting condition. Structural differentiation of mammary gland
Supports lobes and form septa’s Septa anchor the parenchyma to overlying skin. These fibrous bands are called ligament of cooper. Fibrous tissue Interlobar fatty tissue Makes the organ rounded in contour Absent beneath areola and nipple.
Peu de orange
Histology of breast
Arteries Branches of the axillary artery, the internal thoracic artery, and some intercostal arteries. Veins Forms circular venous plexus around the areola Blood drains in veins which accompany the corresponding arteries that supply the breast, i.e. to the axillary, internal thoracic and intercostal veins.
4 th to 6 th intercostal nerves. Innervation of breast
Consists of two sets Draining the parenchyma of breast including nipple and areola Draining overlying skin excluding nipple and areola
75% of lymphatics drain into axillary nodes. 20% drain into parasternal(internal mammary) from both medial and lateral parts of the gland. 5% from lateral and posterior part drain into posterior intercostal nodes. From parencyma of the breast
From the outer part : Axillary nodes From the upper part: Supraclavicular group of lymph nodes From the inner part: Parasternal nodes From the lower part: communicates with subperitoneal lymphatic plexus,drains to sub-diaphragmatic lymph nodes. From the overlying skin
Male breast Composed of duct system without alveoli. Breast tissue doesnot extent beyond the margins of alveoli Hypertrophi of male breast observed in klinefelter’s syndrome. Male breast richly supplied by lymphatics. Prognosis of breast carcinoma in male worst than in females.
At seventh week of intra uterine life two ectodermal milk ridges appear on each side from axillae to inguinal region.
Amastia : bilateral agenesis of mammary gland. Polythelia : supernumerary nipples may be found irregularly over the breast and along milk ridges. Polymastia : accessory breast may occur along milk ridges,occasionally functional. Amastia Polythelia Polymastia
Right accessory breast Left accessory breast Polymastia
Frequency of breast carcinoma at various sites Palpation of axillary region for enlarged nodes
Mammography Only 15-20% of studies are abnormal High % are false positive To be seen on mammogram, tumor is usually 8-10 years old Expensive
Factors Favoring Breast Conserving Therapy : Patient preference Tumor size and location favorable Unifocal tumor Small or no intraductal portion Patient cannot tolerate general anesthesia Factors Favoring Mastectomy : Patient preference Tumor size and location not favorable Multifocal tumor Extensive intraductal component Inability to observe postop Inability to ahcieve negative margins Contraindication for radiotherapy Cosmetic procedures include breast lifts ( mastopexy ), breast augmentation with implants, and procedures that combine both elements. Implants containing either silicone gel or saline are available for augmentation and reconstructive surgeries Treatment of carcinoma of breast