There are three grades of inverted nipples, defined on how easily the nipple may be protracted and the degree of fibrosis existent in the breast as well as the damage it has caused on the milk ducts.

Inverted nipple Grade 1 refers to nipples that can easily be pulled out, by using finger pressure around the areola. The Grade 1 inverted nipple maintains its projections and rarely retracts. Also, Grade 1 inverted nipples may occasionally pop up without manipulation or pressure. Milk ducts are usually not compromised and breast feeding is possible. These are "shy nipples". It is believed to have minimal or no fibrosis. There is no soft-tissue deficiency of the nipple. The lactiferous duct should be normal without any retraction.

Inverted nipple Grade 2 is the nipple which can be pulled out, though not as easily as the Grade 1 inverted nipple but which retracts after pressure is released. Breast feeding is usually possible even though it is more likely to be either hard to get the baby to latch comfortably in the first weeks after birth; extra help may be needed. Grade 2 nipples have a moderate degree of fibrosis. The lactiferous ducts are mildly retracted but do not need to be cut for the release of fibrosis. On histological examination, these nipples have rich collagenous stromata with numerous bundles of smooth muscle. Most people with this problem suffer from inverted nipples Grade 2.

Inverted nipple Grade 3 describes a severely inverted and retracted nipple which can rarely be pulled out physically and which requires surgery in order to be protracted. Milk ducts are often constricted and breast feeding is difficult but not necessarily impossible. With good preparation and help often babies can drink at the breast and milk production is not affected; after breastfeeding often nipples are less or no longer inverted. People with Grade 3 inverted nipples may also struggle with infections, rashes, or problems with nipple hygiene. The fibrosis is remarkable and lactiferous ducts are short and severely retracted. The bulk of soft tissue is markedly insufficient in the nipple. Histologically, there are atrophic terminal duct lobular units and severe fibrosis.

A supernumerary nipple (also known as a third nipple, triple nipple, accessory nipple, polythelia or the related condition: polymastia) is an additional nipple occurring in mammals, including humans. Often mistaken for moles, supernumerary nipples are diagnosed in humans at a rate of approximately 1 in 18 people.

The nipples appear along the two vertical "milk lines," which start in the armpit on each side, run down through the typical nipples and end at the groin. They are classified into eight levels of completeness from a simple patch of hair to a milk-bearing breast in miniature.

"Polythelia" refers to the presence of an additional nipple alone while "polymastia" denotes the much rarer presence of additional mammary glands.

Although usually presenting on the milk line, pseudomamma can appear as far away as the foot.

A possible relationship with mitral valve prolapse has been proposed.

An inverted nipple (occasionally invaginated nipple) is a condition where the nipple, instead of pointing outward, is retracted into the breast. In some cases, the nipple will be temporarily protruded if stimulated. Women and men can have inverted nipples.

In some cases, the accessory breast may not be visible at the surface. In these cases, it may be possible to distinguish their appearance from normal breast tissue with MRI. In other cases, accessory breasts have been known to lactate, as illustrated in a woodcut showing a child nursing at ectopic breast tissue on the lateral thigh.

There is some evidence that the condition may be more common in Native American populations.

Accessory breasts, also known as polymastia, supernumerary breasts, or mammae erraticae, is the condition of having an additional breast. Extra breasts may appear with or without nipples or areolae. It is a condition and a form of atavism which is most prevalent in male humans, and often goes untreated as it is mostly harmless. In recent years, many affected women have had a plastic surgery operation to remove the additional breasts, for purely aesthetic reasons.

A related condition, in which extra nipples form, is called "supernumerary nipple" or "polythelia".

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.

Cracked nipples are classified as a breast disorder. The nipple is not only the structure to delivery milk to the infant, it also contains small, sebaceous glands or Montgomery glands to lubricate the skin of the areola. Cracked nipples are most often associated with breastfeeding and appear as cracks or small lacerations or breaks in the skin of the nipple. In some instances an ulcer will form. The nipple in a nursing mother is in regular contact with a nursing infant. Cracked nipples are trauma to the nipple and can be quite painful. Cracked nipples typically appear three to seven days after the birth.

If the nipples appears to be wedge-shaped, white and flattened, this may indicate that the latch is not good and there is a potential of developing cracked nipples.

Nipple discharge is the release of fluid from the nipples of the breasts. Abnormal nipple discharge may be described as any discharge not associated with lactation. The nature of the discharge may range in color, consistency and composition, and occur in one or both breasts. Although it is considered normal in a wide variety of circumstances it is the third major reason involving the breasts for which women seek medical attention, after breast lumps and breast pain. It is also known to occur in adolescent boys and girls going through puberty.

Cracked nipple (or "nipple trauma") is a condition that can occur in breastfeeding women as a result of a number of possible causes. Developing a cracked nipple can result in soreness, dryness or irritation to, or bleeding of, one or both nipples during breastfeeding. The mother with a cracked nipple can have severe nipple pain when the baby is nursing. This severe pain is a disincentive for continued breastfeeding. The crack can appear as a cut across the tip of the nipple and may extend to its the base. Cracked nipples develop after the birth of the infant and is managed with pharmacological and nonpharmacological treatment.

Amastia refers to a condition where breast tissue, nipple, and areola is absent, either congenitally or iatrogenically. Amastia in girls can be treated with augmentation mammoplasty.

Amastia differs from amazia (which involves only the absence of breast tissue; the nipple and areola remain present), although the two conditions are often (erroneously) thought to be identical. The terms "amastia" and "amazia" are thus often used interchangeably, even though the two conditions are medically different.

A nipple bleb is a blister on the nipple that can be filled with serous fluid or another fluid. It may be pink or light yellow colour. It is thin-walled and may appear as a small blister. It is defined as being more than 5 mm in diameter. It can also be referred to as a bulla. Some clinicians may also include milk blisters as a type of bleb. In addition, a blocked Montgomery glad may also be called a nipple bleb though its cause is different than a milk or serous-filled bleb on the nipple. In some cased the bleb may be associated with an adjacent blocked sebaceous cyst.

Its cause may be due to a blocked pore that leads to seepage of milk or serous fluid under the epidermis. This causes a white 'bump' that appears opaque and shiny. If the bleb continues to block the flow of milk out of the breast it may develop into a blocked milk duct or even mastitis.

A nipple bleb is often treated by the woman herself since a warm saline soak and gentle washing may open the blister and cause it to drain.

Amazia refers to a condition where one or both of the mammary glands is absent (the nipple and areola remain present). This may occur either congenitally or iatrogenically (typically the result of surgical removal and/or radiation therapy). Amazia can be treated with breast implants.

Amazia differs from amastia (the complete absence of breast tissue, nipple, and areola), although the two conditions are often (erroneously) thought to be identical. The terms "amazia" and "amastia" are thus often used interchangeably, even though the two conditions are medically different.

Breast eczema (also known as "Nipple eczema") may affect the nipples, areolae, or surrounding skin, with eczema of the nipples being of the moist type with oozing and crusting, in which painful fissuring is frequently seen, especially in nursing mothers. It will often occur in pregnancy even without breast feeding.

Persisting eczema of the nipple in the middle-aged and elderly needs to be discussed with a doctor, as a rare type of breast cancer called Paget's disease can cause these symptoms.

Fissure of the nipple is a condition that can be caused by friction that can result in soreness, dryness or irritation to, or bleeding of, one or both nipples during breastfeeding. It can also be the result of the friction of clothing against the nipple during physical exercise. This condition is also experienced by women who breastfeed and by surfers who do not wear rash guards.

Genital leiomyomas (also known as "Dartoic leiomyomas") are leiomyomas that originate in the dartos muscles of the genitalia, areola, and nipple.

Specific types of additional body parts include:

- Accessory breast – one or more additional breasts

- Accessory spleen – one or more additional spleens

- Cervical rib – an additional rib

- Diphallia - Having two penes/penises.

- Hermaphroditism – having both sexes' sex organs

- Hyperdontia – additional teeth

- Pelvic digit – a bony growth in the soft tissue of the pelvic region

- Polycephaly – an extra head

- Polydactyly – additional fingers or toes

- Polymelia — an extra arm or leg.

- Polyorchidism – having three or more testicles

- Supernumerary bones – these additional bones are fairly common, particularly in the feet, and are frequently mistaken for fractures on x-rays.

- Supernumerary kidney – a third kidney

- Supernumerary nipples – an additional nipple

- Supernumerary phantom limbs – where the brain acts as though a limb were there, but it is not.

- Syndactyly – webbing between the fingers or toes

- Uterus didelphys – two vaginal canals and/or uteri

Female breast ptosis or sagging is a natural consequence of aging. The rate at which a woman's breasts droop and the degree of ptosis depends on many factors. The key factors influencing breast ptosis over a woman's lifetime are cigarette smoking, her number of pregnancies, gravity, higher body mass index, larger bra cup size, and significant weight gain and loss. Post-menopausal women or people with collagen deficiencies (such as ehlers-danlos) may experience increased ptosis due to a loss of skin elasticity. Many women and medical professionals mistakenly believe that breastfeeding increases sagging. It is also commonly believed that the breast itself offers insufficient support and that wearing a bra prevents sagging which has not been found to be true.

Plastic surgeons categorize the severity of ptosis by evaluating the position of the nipple relative to the infra-mammary fold, the point at which the underside of the breasts attach to the chest wall. In the most advanced stage, the nipples are below the fold and point towards the ground.

Supernumerary body parts are most commonly a congenital disorder involving the growth of an additional part of the body and a deviation from the body plan. Body parts may be easily visible or hidden away, such as internal organs.

Many additional body parts form by the same process as conjoined twins: the zygote begins to split but fails to completely separate. This condition may also be a symptom of repeated occurrences of continuous inbreeding in a genetic line.

Plastic surgeons describe the degree of breast sagging using a "ptosis scale" like the modified "Regnault ptosis scale" below:

- "Grade I: Mild ptosis"—The nipple is at the level of the infra-mammary fold and above most of the lower breast tissue.

- "Grade II: Moderate ptosis"—The nipple is located below the infra-mammary fold but higher than most of the breast tissue hangs.

- "Grade III: Advanced ptosis"—The nipple is below the inframammary fold and at the level of maximum breast projection.

- "Pseudoptosis"—The nipple is located either at or above the infra-mammary fold, while the lower half of the breast sags below the fold. This is most often seen when a woman stops nursing, as her milk glands atrophy, causing her breast tissue to sag.

- "Parenchymal Maldistribution"—The lower breast tissue is lacking fullness, the inframammary fold is very high, and the nipple and areola are relatively close to the fold. This is usually a developmental deformity.

Signs of duct ectasia can include nipple retraction, inversion, pain, and sometimes bloody discharge.

The general presentation is of a skin-covered nodule, papule, or nodule of the skin surface, usually immediately anterior to the auricle. However, it may be anywhere within the periauricular tissues. Bilateral presentation can be seen.

The accessory nail of the fifth toe is a physical trait of the small toe, where a minuscule "sixth toenail" is present in the outer corner of the nail situated on the smallest toe. It is commonly perceived to be especially prevalent amongst Han Chinese;.

The periareolar glands of Montgomery in the breast are also called Montgomery tubercles or Morgagni tubercles. These periareolar glands are small, papular tissue projections at the edge of the areola (nipple).

Obstruction of the Montgomery tubercles may result in an acute inflammation, a clear or light brownish fluid may drain out of the areola (nipple discharge), and an subareolar mass may develop, the cyst of Montgomery.

A cyst of Montgomery may be asymptomatic. Yet, a cyst of Montgomery usually is diagnosed when a female patient, 10–20 years of age, complains to a healthcare professional of breast pain (mastalgia), inflammation or a palpable nodule in the breast. The diagnosis is made clinically, when a palpable nodule is felt in the retroareolar area.

The diagnosis can be confirmed with ultrasonography, frequently showing a simple cyst in the retroareolar area. In some patients, multiple cysts or bilateral cysts may exist. Cysts of Montgomery may have liquid content with an echogenic or calcific sediment.

The lesions presents as a nodule or papule, either sessile or pedunculated. They may be soft or have a cartilaginous structure. By histologic examination, it is a recapitulation of normal external auricle. There will be skin, cartilaginous structures, and cartilage (although the later is not seen in all variants of this disorder). Some investigators believe that the tragus is the only hillock which is derived from the first branchial arch. This is clearly suggestive that true cases of Accessory Auricle represent a true duplication of the hillocks that were part of the second branchial arch. The second ear appears as a mirror image folded forward and lying on the posterior cheek.