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.

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

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).

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.

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.

Sclerosing polycystic adenosis is a rare, reactive inflammatory condition of the salivary glands. It may be mistaken for salivary gland neoplasia. It does not seem to be a fatal disease.

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.

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.

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).

Also called Zuska's disease (only nonpuerperal case), subareolar abscess is a subcutaneous abscess of the breast tissue beneath the areola of the nipple. It is a frequently aseptic inflammation and has been associated with squamous metaplasia of lactiferous ducts.

The term is usually understood to include breast abscesses located in the retroareolar region or the periareolar region, but not those located in the periphery of the breast.

Subareolar abscess can develop both during lactation or extrapuerperal, the abscess is often flaring up and down with repeated fistulation.

Vaginal adenosis is a benign abnormality in the vagina, commonly thought to be caused by intrauterine and neonatal exposure of diethylstilbestrol and other progestagens and nonsteroidal estrogens, however it has also been observed in otherwise healthy women and has been considered at times idiopathic or congenital. Postpubertal lesions have also been observed to grow . It has a rather common incidence, of about 10% of adult women.

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.

Breast tension is a constellation of symptoms involving the breasts including:

- Breast tenderness

- Breast pain

- Breast engorgement

90% of cases are smokers, however only a very small fraction of smokers appear to develop this lesion. It has been speculated that either the direct toxic effect or hormonal changes related to smoking could cause squamous metaplasia of lactiferous ducts. It is not well established whether the lesion regresses after smoking cessation.

Extrapuerperal cases are often associated with hyperprolactinemia or with thyroid problems. Also diabetes mellitus may be a contributing factor in nonpuerperal breast abscess.

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.

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.

The classic feature of gynecomastia is male breast enlargement with soft, compressible, and mobile subcutaneous chest tissue palpated under the areola of the nipple in contrast to softer fatty tissue. This enlargement may occur on one side or both. Dimpling of the skin and nipple retraction are not typical features of gynecomastia. Milky discharge from the nipple is also not a typical finding, but may be seen in a gynecomastic individual with a prolactin secreting tumor. An increase in the diameter of the areola and asymmetry of chest tissue are other possible signs of gynecomastia.

Males with gynecomastia may appear anxious or stressed due to concerns about the possibility of having breast cancer.

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.

Vaginal adenosis is characterised by the presence of metaplastic cervical or endometrial epithelium within the vaginal wall, considered as derived from Müllerian epithelium islets in later life. In women who were exposed to certain chemicals, vaginal adenosis may arise in up to 90%. Since these contraceptives were discontinued, incidence has dropped dramatically. Risk is however still present in subsequent generations due to recent exposure.

It is thought steroid hormones play a stimulatory growth in adenosis formation. Vaginal adenosis is also often observed in adenocarcinoma patients.

Breast engorgement occurs in the mammary glands due to expansion and pressure exerted by the synthesis and storage of breast milk. It is also a main factor in altering the ability of the infant to latch-on. Engorgement changes the shape and curvature of the nipple region by making the breast inflexible, flat, hard, and swollen. The nipples on an engorged breast are flat.

Engorgement usually happens when the breasts switch from colostrum to mature milk (often referred to as when the milk "comes in"). However, engorgement can also happen later if lactating women miss several nursings and not enough milk is expressed from the breasts. It can be exacerbated by insufficient breastfeeding and/or blocked milk ducts. When engorged the breasts may swell, throb, and cause mild to extreme pain.

Engorgement may lead to mastitis (inflammation of the breast) and untreated engorgement puts pressure on the milk ducts, often causing a plugged duct. The woman will often feel a lump in one part of the breast, and the skin in that area may be red and/or warm. If it continues unchecked, the plugged duct can become a breast infection, at which point she may have a fever or flu-like symptoms.

Patients mostly present with a hard lump in one breast without any sign of a systemic disease. Other possible symptoms include nipple retraction, pain, inflammation of the overlying skin, nipple discharge, fistula, enlarged lymph nodes, in rare case peau d'orange-like changes.

Presentation is mostly unilateral although a significant share of cases is bilateral, also in many cases contralateral or bilateral recurrences were documented.

Several cases occurring together with fever, polyarthralgia and erythema nodosum were documented.

Characteristic for idiopathic granulomatous mastitis are multinucleated giant cells and epithelioid histiocytes forming non-caseating granulomas around lobules. Often minor ductal and periductal inflammation is present. The lesion is in some cases very difficult to distinguish from breast cancer and other causes such as infections (tuberculosis, syphilis, corynebacterial infection, mycotic infection), autoimmune diseases (sarcoidosis, granulomatosis with polyangiitis), foreign body reaction and granulomatous reaction in a carcinoma must be excluded.

The condition is diagnosed very rarely. As the diagnosis is a lengthy differential diagnosis of exclusion there is considerable uncertainty about incidence. It has been suspected that some cases diagnosed as IGM in developing countries may have other explanations. On the other hand, IGM is usually diagnosed only after complications and referral to a secondary breast care center so light cases may resolve spontaneously or after symptomatic treatment and thus never be diagnosed as IGM. As a completely pathogen free breast will be exceedingly rare even in completely healthy population there is also uncertainty when to consider pathogens as causative or as mere coincidental finding.

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.

Symptoms: The breasts are swollen and oedematous, and the skin looks shiny and diffusely red. Usually the whole of both breasts are affected, and they are painful. The woman may have a fever that usually subsides in 24 hours. The nipples may become stretched tight and flat which makes it difficult for the baby to attach and remove the milk. The milk does not flow well.

A fever may occur in 15 percent, but is typically less than 39 degrees C and lasts for less than one day.

This condition is also known as constricted breasts, tubular breasts, snoopy breasts (may be considered insulting), herniated areolar complexes, conical breast, domen nipple, lower pole hypoplasia and hypoplastic breasts.

A "breast neoplasm" is an abnormal mass of tissue in the breast as a result of neoplasia. A breast neoplasm may be benign, as in fibroadenoma, or it may be malignant, in which case it is termed breast cancer. Either case commonly presents as a breast lump. Approximately 7% of breast lumps are fibroadenomas and 10% are breast cancer, the rest being other benign conditions or no disease.

Phyllodes tumor is a fibroepithelial tumor which can either benign, borderline or malignant.