The changes in fibrocystic breast disease are characterised by the appearance of fibrous tissue and a lumpy, cobblestone texture in the breasts. These lumps are smooth with defined edges, and are usually free-moving in regard to adjacent structures. The bumps can sometimes be obscured by irregularities in the breast that are associated with the condition. The lumps are most often found in the upper, outer sections of the breast (nearest to the armpit), but can be found throughout the breast. Women with fibrocystic changes may experience a persistent or intermittent breast aching or breast tenderness related to periodic swelling. Breasts and nipples may be tender or itchy.

Symptoms follow a periodic trend tied closely to the menstrual cycle. Symptoms tend to peak in the days and, in severe cases, weeks before each period and decrease afterwards. At peak, breasts may feel full, heavy, swollen, and tender to the touch. No complications related to breastfeeding have been found.

In ICD-10 the condition is called "diffuse cystic mastopathy", or, if there is epithelial proliferation, "fibrosclerosis of breast". Other names for this condition include "chronic cystic mastitis", "fibrocystic mastopathy" and "mammary dysplasia". The condition has also been named after several people (see eponyms below). Since it is a very common disorder, some authors have argued that it should not be termed a "disease", whereas others feel that it meets the criteria for a disease. It is not a classic form of mastitis (breast inflammation).

Symptoms are very variable and may not be present at all in "occult inflammatory breast cancer". Quick onset of symptoms is typical, the breast often looks swollen and red, or “inflamed”, sometimes overnight, and are easy to misdiagnose as mastitis. Invasion of the local lymphatic ducts impairs drainage and causes edematous swelling of the breast. Because the skin of the breast is tethered by the suspensory ligament of Cooper, the accumulation of fluid may cause the skin of the breast to assume a dimpled appearance similar to an orange peel (peau d'orange). A palpable tumor is frequently not obvious as in other forms of breast cancer.

Symptoms may include:

- Sudden swelling of the breast

- Skin changes on breast

- Reddened area with texture resembling the peel of an orange (peau d’orange)

- Nipple retraction (flattened look) or discharge

- Pain in the breast

- Itching of breast

- Swelling of lymph nodes under the arm or in the neck

- Unusual warmth of the affected breast

- Breast is harder or firmer

Other symptoms may rarely include:

- Swelling of the arm

- Breast size may decrease instead of increasing

- Although a dominant mass is present in many cases, most inflammatory cancers present as diffuse infiltration of the breast without a well-defined tumor.

- A lump may become present and grow rapidly

Most patients do not experience all the symptoms of IBC. Not all symptoms need to be present in order to be diagnosed.

Paget's disease of the breast can affect the nipple and areola. Symptoms typically only affect one breast. Symptoms may include:

- "Skin." The first symptom is usually an eczema-like rash. The skin of the nipple and areola may be red, itchy and inflamed. After a period of time, the skin may become flaky or scaly.

- "Discharge." A discharge, which may be straw-colored or bloody, may ooze from the area.

- "Sensation." Some women have a burning sensation. These symptoms usually occur in more advanced stages, when serious destruction of the skin often prompts the patient to consult. Lumps or masses in the breast occur in 50% of the patients. In more advanced stages, the disease may cause tingling, increased sensitivity and pain.

- Nipple changes. The nipple may turn inwards be inverted.

- Breast changes. There may or may not be a lump in the breast, and there may be redness, oozing and crusting, and a sore that does not heal.

The symptoms usually affect the nipple and then spread to the areola and then the breast. It is common for the symptoms to wax and wane.

Most women do not visit the doctor because they assume Paget's disease to be minor contact dermatitis or eczema. A lump or skin irritation that does not seem to heal for over a month indicates that attention by a specialist is needed.

Signs and symptoms of breast cysts include:

- A smooth, easily movable round or oval breast lump with distinct edges

- Breast pain or tenderness in the area of the lump

- Increased lump size and tenderness just before menstruation

- Decreased lump size and resolution of other signs and symptoms after menstruation

- Having one or many simple breast cysts does not increase a person's risk of breast cancer.

Lumps in the breast are often not found during self-examinations or physical exams. However, in some cases they can be felt at touch, especially if they are larger.

Breasts are usually lumpy or nodular as a result of the hormonal changes that women go through during their menstrual cycle. However, new breast lumps should always be referred to a specialist.

Fluid leaking from a cyst, as may happen due to puncture or vigorous compression during mammography, or due to seatbelt injury in the course of an automobile accident, may trigger an aseptic inflammation in the surrounding breast tissue.

Breast diseases can be classified either with disorders of the integument, or disorders of the reproductive system. A majority of breast diseases are noncancerous.

Inflammatory breast cancer is one of the most aggressive types of breast cancer that can occur in women of any age (and,

extremely rarely, in men). It is called inflammatory because it frequently presents with symptoms resembling an inflammation. Despite the name, whether inflammation contributes to the development of "inflammatory breast cancer" remains an area of ongoing research. However it can present with very variable signs and symptoms, frequently without detectable tumors and therefore is often not detected by mammography or ultrasound.

Typical presentation is rapid swelling, sometimes associated by skin changes (peau d'orange), and nipple retraction. Other symptoms include rapid increase in breast size, redness, persistent itching, skin hot to touch. IBC often initially resembles mastitis.

Only about 50-75% cases have the typical presentation. Symptoms can be completely atypical such as acute central venous thrombosis as the sole presenting symptom.

IBC makes up only a small percentage of breast cancer cases (1-6% in the USA). IBC is often diagnosed in younger women although average age of presentation does not differ much from other kinds of breast cancer (average age 57 years). African-Americans are usually diagnosed at younger ages than Caucasian women, and also have a higher risk of getting IBC. Recent advances in therapy have improved the prognosis considerably and at least one third of women will survive the diagnosis by 10 years or longer.

A breast cyst is a fluid-filled sac within the breast. One breast can have one or more breast cysts. They are often described as round or oval lumps with distinct edges. In texture, a breast cyst usually feels like a soft grape or a water-filled balloon, but sometimes a breast cyst feels firm.

Breast cysts can be painful and may be worrisome but are generally benign. They are most common in pre-menopausal women in their 30s or 40s. They usually disappear after menopause, but may persist or reappear when using hormone therapy. They are also common in adolescents.

Breast cysts can be part of fibrocystic disease. The pain and swelling is usually worse in the second half of the menstrual cycle or during pregnancy.

Treating breast cysts is usually not necessary unless they are painful or cause discomfort. In most cases, the discomfort they cause may be alleviated by draining the fluid from the cyst. The cysts form as a result of the growth of the milk glands and their size may range from smaller than a pea to larger than a ping pong ball. Small cysts cannot be felt during a physical examination, and some large cysts feel like lumps. However, most cysts, regardless of their size cannot be identified during physical exams.

Breast cysts are not to be confused with "milk cysts" (galactoceles), which usually appear during weaning.

Fibrosclerosis of the breast is most frequently used to mean sclerosing lobular adenosis of the breast. It is not well known if it is related to non-sclerosing adenosis of the breast (which is normally classified as fibrocystic breast changes) and unlike this it is believed to be correlated with an elevated risk of breast cancer.

Paget's disease of the breast is a type of cancer that outwardly may have the appearance of eczema, with skin changes involving the nipple of the breast. The condition is an uncommon disease accounting for 1 to 4.3% of all breast cancers and was first described by Sir James Paget in 1874. The condition in itself often appears innocuous, limited to a surface appearance and it is sometimes dismissed, although actually indicative of underlying breast cancer.

Breast pain is a medical symptom that is most often associated with a developing disease or condition of the breast. These are usually benign breast diseases or conditions such as mastalgia, mastodynia, and fibrocystic breast changes. These disorders are painful and associated with lumps. Some breast pain is normal and associated with the changes that accompany puberty, pregnancy, lactation and menopause. The pain can be in one breast or both. The pain may constant, cyclical, or present only on palpation or when it is touched.

Male breast cancer (male breast neoplasm) is a rare cancer in males that originates from the breast. Many males with breast cancer have inherited a "BRCA" mutation, but there are other causes, including alcohol abuse and exposure to certain hormones and ionizing radiation.

As it presents a similar pathology as female breast cancer, assessment and treatment relies on experiences and guidelines that have been developed in female patients. The optimal treatment is currently not known.

These may be caused among others by trauma, secretory stasis/milk engorgement, hormonal stimulation, infections or autoimmune reactions.

Repeated occurrence unrelated to lactation requires endocrinological examination.

- bacterial mastitis

- mastitis from milk engorgement or secretory stasis

- mastitis or mumps

- chronic subareolar abscess

- tuberculosis of the breast

- syphilis of the breast

- retromammary abscess

- actinomycosis of the breast

- duct ectasia syndrome

- breast engorgement

Comedo mastitis is a very rare form similar to granulomatous mastitis but with tissue necrosis. Because it is so rare it may be sometimes confused with comedo carcinoma of the breast although the conditions appear to be completely unrelated.

Fibroadenomas, are benign breast tumours characterized by an admixture of stromal and epithelial tissue. Breasts are made of lobules (milk producing glands) and ducts (tubes that carry the milk to the nipple). These are surrounded by glandular, fibrous and fatty tissues. Fibroadenomas develop from the lobules. The glandular tissue and ducts grow over the lobule to form a solid lump.

Since both fibroadenomas, and breast lumps as a sign of breast cancer can appear similar, it is recommended to perform ultrasound analyses and possibly tissue sampling with subsequent histopathologic analysis in order to make a proper diagnosis. Unlike typical lumps from breast cancer, fibroadenomas are easy to move, with clearly defined edges.

Fibroadenomas are sometimes called breast mice or a breast mouse owing to their high mobility in the breast.

Fibroadenomas are partially hormone-related and frequently regress after menopause.

Higher intake of fruits and vegetables, higher number of live births, lower use of oral contraceptives and moderate exercise are associated with lower frequency of fibroadenomas.

As in females, infiltrating ductal carcinoma is the most common type. While intraductal cancer, inflammatory carcinoma, and Paget's disease of the nipple have been described, lobular carcinoma in situ has not been seen in males. Breast cancer in males spreads via lymphatics and blood stream like female breast cancer. Accordingly, the TNM staging system for breast cancer is the same for males and females.

Size of the lesion and lymph node involvement determine prognosis; thus small lesions without lymph node involvement have the best prognosis. Estrogen receptor and progesterone receptor status and HER2/neu (Human Epidermal Growth Factor Receptor 2) gene amplification need to be reported as they may affect treatment options. About 85% of all male breast cancers are estrogen receptor–positive, and 70% are progesterone receptor–positive.

Ruling out the other possible causes of the pain is one way to differentiate the source of the pain. Breast pain can be due to:

- angina pectoris

- anxiety and depression

- bra

- blocked milk duct

- breastfeeding

- chest wall muscle pain

- consensual, rough sex

- costal chondritis (sore ribs)

- cutaneous candida infection

- duct ectasia (often with nipple discharge)

- engorgement

- fibroadenoma

- fibrocystic breast changes

- fibromyalgia

- gastroesophageal reflux disease

- herpes infection

- hormone replacement therapy

- mastalgia

- mastitis or breast infection

- menopause

- menstruation and Premenstrual syndrome

- perimenopause

- neuralgia

- pregnancy

- physical abuse

- pituitary tumor (often with nipple discharge)

- puberty in both girls and boys

- sexual abuse

- shingles

- sore nipples and cracked nipples

- surgery or biopsy

- trauma (including falls)

Medications can be associated with breast pain and include:

- Oxymetholone

- Chlorpromazine

- Water pills (diuretics)

- Digitalis preparations

- Methyldopa

- Spironolactone

Diagnostic testing can be useful. Typical tests used are mammogram, excisional biopsy for solid lumps, fine-needle aspiration and biopsy, pregnancy test, ultrasonography, and magnetic resonance imaging (MRI).

Characteristic for granulomatous mastitis are multinucleated giant cells and epithelioid histiocytes around lobules. Often minor ductal and periductal inflammation is present. The lesion is in some cases very difficult to distinguish from breast cancer.

The first noticeable symptom of breast cancer is typically a lump that feels different from the rest of the breast tissue. More than 80% of breast cancer cases are discovered when the woman feels a lump. The earliest breast cancers are detected by a mammogram. Lumps found in lymph nodes located in the armpits can also indicate breast cancer.

Indications of breast cancer other than a lump may include thickening different from the other breast tissue, one breast becoming larger or lower, a nipple changing position or shape or becoming inverted, skin puckering or dimpling, a rash on or around a nipple, discharge from nipple/s, constant pain in part of the breast or armpit, and swelling beneath the armpit or around the collarbone. Pain ("mastodynia") is an unreliable tool in determining the presence or absence of breast cancer, but may be indicative of other breast health issues.

Inflammatory breast cancer is a particular type of breast cancer which can pose a substantial diagnostic challenge. Symptoms may resemble a breast inflammation and may include itching, pain, swelling, nipple inversion, warmth and redness throughout the breast, as well as an orange-peel texture to the skin referred to as "peau d'orange". As inflammatory breast cancer does not present as a lump there can sometimes be a delay in diagnosis.

Another reported symptom complex of breast cancer is Paget's disease of the breast. This syndrome presents as skin changes resembling eczema, such as redness, discoloration, or mild flaking of the nipple skin. As Paget's disease of the breast advances, symptoms may include tingling, itching, increased sensitivity, burning, and pain. There may also be discharge from the nipple. Approximately half of women diagnosed with Paget's disease of the breast also have a lump in the breast.

In rare cases, what initially appears as a fibroadenoma (hard, movable non-cancerous lump) could in fact be a phyllodes tumor. Phyllodes tumors are formed within the stroma (connective tissue) of the breast and contain glandular as well as stromal tissue. Phyllodes tumors are not staged in the usual sense; they are classified on the basis of their appearance under the microscope as benign, borderline, or malignant.

Occasionally, breast cancer presents as metastatic disease—that is, cancer that has spread beyond the original organ. The symptoms caused by metastatic breast cancer will depend on the location of metastasis. Common sites of metastasis include bone, liver, lung and brain. Unexplained weight loss can occasionally signal breast cancer, as can symptoms of fevers or chills. Bone or joint pains can sometimes be manifestations of metastatic breast cancer, as can jaundice or neurological symptoms. These symptoms are called "non-specific", meaning they could be manifestations of many other illnesses.

Most symptoms of breast disorders, including most lumps, do not turn out to represent underlying breast cancer. Fewer than 20% of lumps, for example, are cancerous, and benign breast diseases such as mastitis and fibroadenoma of the breast are more common causes of breast disorder symptoms. Nevertheless, the appearance of a new symptom should be taken seriously by both patients and their doctors, because of the possibility of an underlying breast cancer at almost any age.

When gigantomastia occurs in young women during puberty, the medical condition is known as "juvenile macromastia" or "juvenile gigantomastia" and sometimes as "virginal breast hypertrophy" or "virginal mammary hypertrophy". Along with the excessive breast size, other symptoms include red, itchy lesions and pain in the breasts. A diagnosis is made when an adolescent's breasts grow rapidly and achieve great weight usually soon after her first menstrual period. Some doctors suggest that the rapid breast development occurs before the onset of menstruation.

Some women with virginal breast hypertrophy experience breast growth at a steady rate for several years, after which the breasts rapidly develop exceeding normal growth. Some adolescent females experience minimal or negligible breast growth until their breasts suddenly grow very rapidly in a short period of time. This may cause considerable physical discomfort. Women suffering VBH often experience an excessive growth of their nipples as well. In severe cases of VBH, hypertrophy of the clitoris occurs.

At the onset of puberty, some females with who have experienced little or no breast development can reportedly reach three or more cup sizes within a few days (see below).

Radial scars are diagnosed by a microscopic examination of excised tissue, i.e. they are diagnosed by pathologists based on their histomorphology.

Nipple discharge refers to any fluid that seeps out of the nipple of the breast. Discharge from the nipple does not occur in lactating women. And discharge in non-pregnant women or women who are not breasfeeding may not cause concern. Men that have discharge from their nipples are not typical. Discharge from the nipples of men or boys may indicate a problem. Discharge from the nipples can appear without squeezing or may only be noticeable if the nipples are squeezed. One nipple can have discharge while the other does not. The discharge can be clear, green, bloody, brown or straw-colored. The consistenct can be thick, thin, sticky or watery.

Some cases of nipple discharge will clear on their own without treatment. Nipple discharge is most often not cancer (benign), but rarely, it can be a sign of breast cancer. It is important to find out what is causing it and to get treatment. Here are some reasons for nipple discharge:

- Pregnancy

- Recent breastfeeding

- Rubbing on the area from a bra or t-shirt

- Trauma

- Infection

- Inflammation and clogging of the breast ducts

- Noncancerous pituitary tumors

- Small growth in the breast that is usually not cancer

- Severe underactive thyroid gland (hypothyroidism)

- Fibrocystic breast (normal lumpiness in the breast)

- Use of certain medicines

- Use of certain herbs, such as anise and fennel

- Widening of the milk ducts

- Intraductal pipilloma

- Subareolar abscess

- Mammary duct ectasia

- Pituitary tumor

Sometimes, babies can have nipple discharge. This is caused by hormones from the mother before birth. It usually goes away in 2 weeks. Cancers such as Paget disease (a rare type of cancer involving the skin of the nipple) can also cause nipple discharge.

Nipple discharge that is NOT normal is bloody, comes from only one nipple, or comes out on its own without squeezing or touching the nipple. Nipple discharge is more likely to be normal if it comes out of both nipples or happens when the nipple is squeezed. Squeezing the nipple to check for discharge can make it worse. Leaving the nipple alone may make the discharge stop.

The indication is a breast weight that exceeds approximately 3% of the total body weight. There are varying definitions of what is considered to be excessive breast tissue, that is the expected breast tissue plus extraordinary breast tissue, ranging from as little as up to with most physicians defining macromastia as excessive tissue of over . Some resources distinguish between macromastia (Greek, "macro": large, "mastos": breast), where excessive tissue is less than 2.5 kg, and gigantomastia (Greek, "gigantikos": giant), where excessive tissue is more than 2.5 kg. The enlargement can cause muscular discomfort and over-stretching of the skin envelope, which can lead in some cases to ulceration.

Hypertrophy of the breast can affect the breasts equally, but usually affects one breast more than the other, thereby causing asymmetry, when one breast is larger than the other. The condition can also individually affect the nipples and areola instead of or in addition to the entire breast. The effect can produce a minor size variation to an extremely large breast asymmetry. Breast hypertrophy is classified in one of five ways: as either pubertal (virginal hypertrophy), gestational (gravid macromastia), in adult women without any obvious cause, associated with penicillamine therapy, and associated with extreme obesity. Many definitions of macromastia and gigantomastia are based on the term of "excessive breast tissue", and are therefore somewhat arbitrary.

Most of the women who develop DCIS do not experience any symptoms. The majority of cases (80-85%) are detected through screening mammography. The first signs and symptoms may appear if the cancer advances. Because of the lack of early symptoms, DCIS is most often detected at screening mammography.

In a few cases, DCIS may cause:

- A lump or thickening in or near the breast or under the arm

- A change in the size or shape of the breast

- Nipple discharge or nipple tenderness; the nipple may also be inverted, or pulled back into the breast

- Ridges or pitting of the breast; the skin may look like the skin of an orange

- A change in the way the skin of the breast, areola, or nipple looks or feels such as warmth, swelling, redness or scaliness.