Introduction
Breast diseases form a major proportion of surgical referrals, forming approximately 20% of outpatient workload. The main factor for this is this suspicion of carcinoma of the breast, which still remains the commonest malignancy in females. It is important to note that the majority of patients who attend clinic will have benign disease.
Breast cancer is by far the most common cancer in women accounting for about 18% of all female cancers and about 45,000 diagnosed annually in the United Kingdom. Age is the single most important risk factor for developing breast cancer, and only a minority of all breast cancers occur in women under 40-years-old.
Anatomy
Breasts are modified sweat glands that produce milk in women. Each breast usually has one nipple surrounded by the areola. The lactiferous lobules which produce the milk lay deep in the breast tissue and are connected to the nipple areola complex by approximately 16 lactiferous ducts, each with its own opening. The lobules are located throughout the breast, with the majority found in close proximity to the nipple. The remainder of the breast consists of connective tissue, adipose tissue, and the suspensory Coopers Ligament.
The breasts sit over the pectoralis major muscle and have its superior margin at the level of the 2nd rib to the level of the 6th rib inferiorly. Medially it extends to the lateral border of the sternum and laterally extends diagonally upwards into the axilla, and is often referred to as the axillary tail.
The main arterial supplies to the breast are from the internal thoracic artery (branch of the subclavian artery), intercostals arteries, thoracodorsal artery and thoracoacromial artery.
The venous drainage of the breast is mainly to the axillary vein, but as with the arterial supply, there are other vessels. There is some drainage to the internal thoracic vein and the intercostals veins. It is important to note that the intercostals veins communicate with the valveless vertebral venous plexus of Batson, as this complex plexus communicates with the spinal column and can be a route for metastasis.
The anterior and lateral cutaneous branches of the fourth through sixth intercostal nerves innervate the breast. The nipple is supplied by the T4 dermatome. The major lymphatic drainage of the breast is the axillary nodes with a small percentage going to the internal thoracic nodes.
Breast Development
Females develop breasts during puberty, secondary to cyclical hormones, mainly oestrogen. This promotes glandular tissue development and fat deposition which will be essential for lactation in later life.
Breast composition and size is normally a dynamic process, which regularly changes. Changes occur in both the lobular and ductal systems. There are a spectrum of factors that result in change in breast size, and shape.
As breasts are mostly composed of adipose tissue, their size can change over time. This occurs for a number of reasons, most obviously when a girl grows during puberty, pregnancy, menstrual cycle, weight gain or loss.
Abnormal breast development can occur due to a number of reasons; Virginal breast hypertrophy involves excessive growth of the breasts and in some cases the continued growth beyond the usual pubescent age. Conversely, breast hypoplasia occurs where one or both breasts fail to develop.
During pregnancy, there is an increase in placental oestrogen secretion, which results in an increase in the ductal system and an increase in fat deposition. Placental oestrogens are not alone in causing these changes; a variety of factors including prolactin, growth hormone, glucocorticoid and insulin have also demonstrated similar breast growth properties. In addition to becoming larger, the breasts generally become firmer, mainly due to hypertrophy of the mammary gland in response to prolactin. The size of the nipples may increase noticeably and their pigmentation may become darker. Pregnancy also results in an increase in progesterone secretion, resulting in promotion of lobular growth and development of alveolar secretory function.
The breasts generally revert to approximately their previous size after pregnancy, although there may be some increased sagging and stretch marks. Sagging of the breasts occur due to elongation of the ligaments, a natural process that can occur over time. The size of a woman’s breasts may fluctuate during the menstrual cycle, exacerbated by pre-menstrual water retention.
Breast disease
Most women presenting to the breast clinic will have benign disease but a small percentage will be diagnosed as having breast cancer. Patients will often present with the following symptoms:
- Lump
- Thickening/nodularity
- Breast pain
- Nipple discharge
- Asymmetry
- Skin changes
These patients are generally classified into two categories based on their age; less than 35 years and 35 years and above. Patients aged less than 35 years will routinely have an ultrasound scan of the breast and those 35 years and above will have both mammogram and ultrasound scan. All patients presenting with focal breast abnormalities should have a triple assessment. Triple assessment consists of:
- Clinical history and examination by a breast physician.
- Breast imaging assessment with USS and or mammogram.
- Pathology assessment using fine needle aspiration biopsy (FNAB) or core needle biopsy (the latter is preferred).
Magnetic resonance imaging (MRI) is only used in specific cases such as screening of young women at high risk of developing breast cancer, invasive lobular carcinoma, implants etc. The triple assessment provides accurate out patient diagnosis and so ensures a very high percentage of non operative diagnosis. One stop clinics prevent multiple patient visits for results and USS guided biopsies are preferred to freehand biopsies because of better accuracy.
Clinical examination incorporates undertaking a detailed history and detailed systematic examination of the breast and axilla. Numerous factors including early menarche, late menopause, and prolonged usage of the combined oral contraceptive pill/hormone replacement therapy (HRT), positive family history of breast and or ovarian cancer etc are important considerations.
The key message to reinforce is that diagnosis of breast disease cannot be made on clinical assessment alone, but patients require triple assessment as stated above.
Pregnancy/lactation
Some breast diseases are pregnancy related. Pregnancy results in breast engorgement and proliferation of ductal and lobular structures. These processes in themselves can cause symptoms, or lead to complications.
Physiological discharge is usually a mild clear/light discharge from multiple ducts with normal prolactin levels. Women can be reassured.
Galactorrhoea causes bilateral cloudy white nipple discharge long after stopping breast feeding. This contains a milky substance and is usually located in the lactiferous lobules. The outlet of the lobule usually has a ductal plug that prevents the milk from escaping. It is usually self limiting and resolves on cessation of breast feeding. It is sterile and usually does not get infected. Drainage is not advised due to the high likelihood of recollection and infection. Serum prolactin levels should be obtained. Bloody discharge may occur during pregnancy due to hypervascularity. Triple assessment is usually normal and no treatment is required.
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