Next Lesson - Malignant Breast Disease
Core
There are lots of different conditions involving the breast and it is crucial to identify which of these are benign, and which are malignant.
Benign conditions do not themselves invade (grow into nearby tissue) or metastasise (spread to other parts of the body), and so are often simpler to manage. However, some benign conditions are associated with an increased future risk of malignancy (cancer), which can blur the distinction in clinical practice. Benign conditions include infections, developmental disorders and tumours, with each condition managed differently, from medical treatment to surgical treatment, to being left alone.
Developmental disorders are often associated with accessory breast tissue (known as polymastia) seen in an area that is not normally associated with the breast. A related problem is extra nipples, known as polythelia. Both usually present along the embryological mammary streak or “milk lines” (the paths along which breast tissue forms in the embryo) as depicted below.
Diagram - The embryological mammary streak path
Creative commons source by The Geneva Foundation for Medical Education and Research [CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0)]
Gynaecomastia is the enlargement of the male breast due to a relative decrease in testosterone and increase in oestrogen. It can be either unilateral or bilateral. Gynaecomastia itself is benign and does not usually increase the risk of breast cancer, although breast cancer can still occur in men and suspicious features require assessment.
It is mainly seen in neonates (newborn babies), in puberty and in older men. In neonates, it is due to increased maternal oestrogen in the baby’s circulation. In puberty, it is transient (temporary) because oestrogen production peaks before testosterone. In older men, it is linked to falling testosterone production with age. It is also seen in those with excessive alcohol consumption, where cirrhosis (scarring of the liver) reduces liver function so that oestrogen cannot be metabolised. It is also a known side effect of some drugs such as spironolactone (a diuretic) and anabolic steroids (hormones taken to build muscle).
The most common benign breast disorder is fibrocystic change, occurring most commonly in women aged 20 to 50.
It presents with pain and masses in the upper outer quadrant of the breasts, most prominent in the week before menstruation. Symptoms ease at the start of the period. This discomfort is thought to be related to hormonal changes across the menstrual cycle, with a combination of localised fibrosis, inflammation and cyst formation in the breast tissue. The exact cause is not fully understood.
If the symptoms are bilaterally symmetrical and synchronised to the woman’s menstrual cycle, a diary recording the symptoms may be helpful, and examination should ideally be performed mid-cycle. Once a suspicious lump has been ruled out and the picture fits fibrocystic change, the patient should be reassured and then receive symptomatic management. This includes analgesia (painkillers) and a well-fitting bra. If a symptomatic cyst needs invasive management, the cyst often resolves after fine needle aspiration (draining the fluid with a thin needle).
Duct ectasia involves the dilation of one or more of the lactiferous ducts (the milk ducts) in the breast, leading to blockage of the duct and inflammation. Key features include nipple discharge (intermittent, and ranging in colour from white or yellow to green or black) and retraction of the nipple (the nipple turning inwards). Other features are chronic periductal inflammation (long-term inflammation around the duct) and abscess formation. Bloody discharge is not a typical feature of duct ectasia and needs assessment. It is more often caused by an intraductal papilloma (a small growth inside a milk duct), and it can also be a sign of cancer. Duct ectasia overlaps with periductal mastitis (inflammation around the milk ducts), which is more common in smokers, and the two can be hard to tell apart.
Management is usually conservative (non-surgical), with reassurance and symptomatic treatment. Surgical excision (removal) of the affected duct may be considered for persistent or troublesome symptoms, and referral is often made to exclude malignancy when features overlap with breast cancer. This referral is commonly made on the suspected cancer pathway (the fast-track route for possible cancer). NICE advises it for people aged 30 and over with an unexplained breast lump. It is also advised for people aged 50 and over with nipple discharge, retraction or other changes of concern in one nipple only.
Infections and Cysts of the Breast
Acute mastitis is an inflammatory condition of the breast that predominantly occurs during breastfeeding. The lactiferous sinuses (the milk-collecting spaces behind the nipple) can become infected by bacteria (commonly Staphylococcus aureus, a common skin bacterium) entering via the nipple. The breast becomes painful, swollen and erythematous (red). Patients will often present systemically unwell (unwell throughout the body, not just in the breast) with signs like fever, rigors (shaking chills) and fatigue.
Infection is most likely if stasis of the milk (milk not draining, so it stays in the breast) occurs. This happens through blocked ducts or unilateral breastfeeding (feeding from one breast only, so milk builds up in the other).
Initial management of mastitis is to return the flow of milk in the ducts through frequent and effective milk removal. This can often be done by the woman at home. She should keep feeding the child, including from the affected breast (there is little risk of passing the infection on). If feeding is too painful, she can hand express enough milk to match the baby’s needs. Breast pumps should be used as little as possible, because they may worsen swelling. Any pressure on the breast should be gentle, so firm massage is avoided. Cold compresses (about 10 minutes every hour) can help when the breast is swollen, and paracetamol or ibuprofen can ease the pain. If symptoms have not improved after 24 hours despite effective milk removal, or the nipple is cracked and looks infected, antibiotics such as flucloxacillin (a penicillin-type antibiotic) are prescribed. Erythromycin or clarithromycin is used if the woman is allergic to penicillin.
Mastitis can occur without breastfeeding (non-lactational mastitis). It can relate to skin irritation of the breast, such as through eczema (itchy, inflamed skin), or to periductal mastitis (inflammation around the milk ducts), which is linked to smoking. In these women, antibiotics are indicated in all cases. NICE Clinical Knowledge Summaries (CKS) suggests co-amoxiclav (a broad-spectrum antibiotic) first line, because the bacteria involved are more varied than in breastfeeding women and include anaerobes (bacteria that grow without oxygen). Local policy also guides the choice.
If the infection is left untreated, it can lead to a breast abscess (a collection of pus) and sepsis. It is important to check the observations of every patient presenting with mastitis. A suspected abscess needs urgent referral to a general surgeon, and signs of sepsis need hospital admission. It is also important to look for an underlying cause in older patients, as stasis of milk is far less likely to be the cause. There is also an increased risk of an underlying pathology (such as cancer).
If the red, painful and swollen breast does not improve with antibiotics, a referral should be made to rule out inflammatory breast cancer. This cancer can look like mastitis because cancer cells spread through the lymph vessels of the breast (diffuse lymphatic infiltration).
Cysts in the breast are difficult to distinguish from solid tumours on examination, meaning that referral for imaging should be made. Cysts are fluid-filled sacs often surrounded by fibrous tissue, presenting between the ages of 35 and 50 as mobile and smooth masses. Symptomatic cysts can be aspirated (drained with a needle) for relief; surgical removal is rarely required.
Fat necrosis presents as irregular, firm, palpable masses (lumps that can be felt), with or without skin changes. These masses can mimic breast cancer clinically, and so should be referred for further imaging. The necrosis (death of fat tissue) follows an inflammatory response after trauma to, or surgery on, the breast, so always ask about a history of either.
Image - Histological (seen under the microscope) breast tissue showing fat necrosis. There are necrotic adipocytes (dead fat cells) surrounded by an inflammatory response with cholesterol clefts (needle-shaped gaps left where cholesterol crystals have dissolved)
Creative commons source by Department of Pathology, Calicut Medical College [CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0)]
Fibroadenomas are the most common benign tumour of the breast and occur at any age, but more prominently under the age of 30.
They are fibroepithelial tumours (growths made of both fibrous and epithelial tissue) that arise in the lobules (the milk-producing units) of the breast. They are formed by a proliferation (an increase in the number of cells) of both stromal (supporting, connective) and epithelial (lining and glandular) elements. They are classified as benign tumours, representing a benign neoplastic proliferation (a non-cancerous new growth of cells) of stromal and epithelial tissue.
They can be multiple and bilateral (in both breasts). They feel smooth, round, non-tender and highly mobile. On ultrasound scans or mammograms (X-ray images of the breast), they appear as masses with regular borders.
Some contain cysts (fluid-filled spaces) and are called complex fibroadenomas. Hormones appear to play a role (hormonal aetiology, meaning a hormonal cause). Studies of the oral contraceptive pill have reported both a lower and a higher risk of fibroadenoma, and hormone replacement therapy has sometimes been reported to enlarge existing fibroadenomas. It is possible for the tumours to grow very large and replace most of the breast. When they are removed they appear rubbery and grey-white. Fibroadenomas do not metastasise, and they have a very low malignant potential. Women with complex fibroadenomas have a higher long-term risk of breast cancer.
Image - Ultrasound image of a fibroadenoma
Creative commons source by Nevit Dilmen (talk) [CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0)]
Phyllodes tumours are rare fibroepithelial tumours (made of both stromal and epithelial tissue) which present in older women, most often aged 40 to 50. They are graded as benign, borderline or malignant. Most are benign, but they have a higher probability of becoming malignant than fibroadenomas. In case series (reports on groups of patients) from specialist centres, roughly one in five to one in three were malignant. Malignant phyllodes tumours are cancers, unlike the other conditions in this article. They can be very large and involve the entire breast.
They are nodules of proliferating stroma covered by "leaf-like" epithelium. The stroma in phyllodes tumours contains more atypical (abnormal-looking) and mitotic cells (cells that are dividing) than it would in a fibroadenoma.
Treatment is excision (surgical removal) with a wide margin (a rim of normal tissue taken with the tumour) to try and prevent local recurrence of the tumour. The malignant types can recur locally and, less often, metastasise through the bloodstream, mainly to the lungs and bones, meaning fast investigation and diagnosis is important.
Other generalised benign stromal tumours like lipomas (fatty tumours), leiomyomas (smooth muscle tumours) and hamartomas (disorganised overgrowths of normal tissue) can also occur in the breast.
Investigating Benign Breast Disorders
It is important to treat any breast abnormality with a high index of suspicion (assume it could be cancer until tests show otherwise), because it is very difficult to confirm whether an abnormality is benign from examination alone. Breast clinics use triple assessment: clinical examination, imaging and, where needed, a biopsy. Imaging is by mammography (an X-ray of the breast) or ultrasound scan. Ultrasound is more useful in women under 40 and in men. NICE advises a suspected cancer pathway referral (a fast-track referral for possible cancer) for people aged 30 and over with an unexplained breast lump. For people under 30, non-urgent referral can be considered.
Two common benign breast disorders that can often be managed in primary care are:
- Mastitis - infection of the breast can usually be treated in primary care. Refer if it does not resolve. Refer urgently to a general surgeon if an abscess is suspected, admit if there are signs of sepsis, and use the suspected cancer pathway if cancer is suspected.
- Fibrocystic change - this may not need referral if the symptoms are clearly cyclical and the breast examination is normal.
Any other breast lump or mass discussed in this article cannot be definitely distinguished from a malignant lesion on palpation (examination by touch) alone, and should be referred for imaging. Gynaecomastia in newborn babies or in puberty usually goes away by itself.
Edited by: Dr. Maddie Swannack
Reviewed by: Dr. Thomas Burnell and Dr. Marcus Judge
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