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.

Atypical ductal hyperplasia, abbreviated ADH, is the term used for a benign lesion of the breast that indicates an increased risk of breast cancer.

The name of the entity is descriptive of the lesion; ADH is characterized by cellular proliferation (hyperplasia) within one or two breast ducts and (histomorphologic) architectural abnormalities, i.e. the cells are arranged in an abnormal or atypical way.

In the context of a core (needle) biopsy, ADH is considered an indication for a breast lumpectomy, also known as a surgical (excisional) biopsy, to exclude the presence of breast cancer.

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.

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.

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.

ADH, generally, is asymptomatic. It usually comes to medical attention on a screening mammogram, as a non-specific suspicious abnormality that requires a biopsy.

The symptoms produced by metastatic breast cancer vary by the location of the metastases. For instance:

- Metastatic disease to the bone causes severe, progressive pain, and, less commonly, pathological fracture, erythema over the affected bone, and swelling.

- Metastatic breast cancer to the brain causes the following symptoms: persistent, progressively worsening headache, visual changes, seizures, nausea or vomiting, vertigo, behavioral and personality changes, and increased intracranial pressure.

- Metastatic disease to the liver causes jaundice, elevated liver enzymes, abdominal pain, loss of appetite, nausea, and vomiting

- Metastatic breast cancer to the lung or pleura causes chronic cough, dyspnea, abnormal chest X-ray, and chest pain.

- Other nonspecific systemic symptoms of metastatic breast cancer include fatigue, malaise, weight loss, and poor appetite.

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.

Carcinoma "in situ (CIS), also known as in situ" neoplasm, is a group of abnormal cells. While they are a form of neoplasm there is disagreement over whether CIS should be classified as cancer. This controversy also depends on the exact CIS in question (i.e. cervical, skin, breast). Some authors do not classify them as cancer, however, recognizing that they can potentially become cancer. Others classify certain types as a non-invasive form of cancer. The term "pre-cancer" has also been used.

These abnormal cells grow in their normal place, thus ""in situ"" (from Latin for "in its place"). For example, carcinoma "in situ" of the skin, also called Bowen's disease, is the accumulation of dysplastic epidermal cells within the epidermis only, that has failed to penetrate into the deeper dermis. For this reason, CIS will usually not form a tumor. Rather, the lesion is flat (in the skin, cervix, etc.) or follows the existing architecture of the organ (in the breast, lung, etc.). Exceptions include CIS of the colon (polyps), the bladder (preinvasive papillary cancer), or the breast (ductal carcinoma "in situ" or lobular carcinoma "in situ").

Many forms of CIS have a high probability of progression into cancer, and therefore removal may be recommended; however, progression of CIS is known to be highly variable and not all CIS becomes invasive cancer.

In the TNM classification, carcinoma "in situ" is reported as TisN0M0 (stage 0).

These terms are related since they represent the steps of the progression toward cancer:

- Dysplasia is the earliest form of precancerous lesion recognizable in a biopsy. Dysplasia can be low-grade or high-grade. High-grade dysplasia may also be referred to as carcinoma "in situ".

- Invasive carcinoma, usually simply called cancer, has the potential to invade and spread to surrounding tissues and structures, and may eventually be lethal.

Pancreatic serous cystadenoma, also known as serous cystadenoma of the pancreas and serous microcystic adenoma, a benign tumour of pancreas. It is usually found in the head of the pancreas, and may be associated with von Hippel-Lindau syndrome.

In contrast to some of the other cyst-forming tumors of the pancreas (such as the intraductal papillary mucinous neoplasm and the mucinous cystic neoplasm), serous cystic neoplasms are almost always entirely benign. There are some exceptions; rare case reports have described isolated malignant serous cystadenocarcinomas. In addition, serous cystic neoplasms slowly grow, and if they grow large enough they can press on adjacent organs and cause symptoms.

Pathologists classify serous cystic neoplasms into two broad groups. Those that are benign, that have not spread to other organs, are designated "serous cystadenoma". Serous cystadenomas can be further sub-typed into microcystic, oligocystic (or macrocystic), solid, mixed serous-endocrine neoplasm, and VHL-associated serous cystic neoplasm. This latter classification scheme is useful because it highlights the range of appearances and the clinical associations of these neoplasms. Serous cystic neoplasms that have spread ("metastasized") to another organ are considered malignant and are designated "serous cystadenocarcinoma".

A urogenital neoplasm is a tumor of the urogenital system.

Types include:

- Cancer of the breast and female genital organs: (Breast cancer, Vulvar cancer, Vaginal cancer, Cervical cancer, Uterine cancer, Endometrial cancer, Ovarian cancer)

- Cancer of the male genital organs (Carcinoma of the penis, Prostate cancer, Testicular cancer)

- Cancer of the urinary organs (Renal cell carcinoma, Bladder cancer)

Triple-negative breast cancer (sometimes abbreviated TNBC) refers to any breast cancer that does not express the genes for estrogen receptor (ER), progesterone receptor (PR) or Her2/neu. This makes it more difficult to treat since most hormone therapies target one of the three receptors, so triple-negative cancers often require combination therapies. Triple negative is sometimes used as a surrogate term for basal-like; however, more detailed classification may provide better guidance for treatment and better estimates for prognosis.

Triple-negative breast cancers comprise a very heterogeneous group of cancers. There are conflicting information over prognosis for the various subtypes but it appears that the Nottingham prognostic index is valid and hence general prognosis is rather similar with other breast cancer of same stage, except that more aggressive treatment is required. Some types of triple-negative breast cancer are known to be more aggressive with poor prognosis, while other types have very similar or better prognosis than hormone receptor positive breast cancers. Pooled data of all triple-negative subtypes suggest that with optimal treatment 20-year survival rates are very close to those of hormone positive cancer.

Triple-negative breast cancers have a relapse pattern that is very different from hormone-positive breast cancers: the risk of relapse is much higher for the first 3–5 years but drops sharply and substantially below that of hormone-positive breast cancers after that. This relapse pattern has been recognized for all types of triple-negative cancers for which sufficient data exists although the absolute relapse and survival rates differ across subtypes.

Neoplasm is an abnormal growth of tissue which, if it forms a mass, is commonly referred to as a tumor. This abnormal growth (neoplasia) usually but not always forms a mass.

ICD-10 classifies neoplasms into four main groups: benign neoplasms, in situ neoplasms, malignant neoplasms, and neoplasms of uncertain or unknown behavior. Malignant neoplasms are also simply known as cancers and are the focus of oncology.

Prior to the abnormal growth of tissue, as neoplasia, cells often undergo an abnormal pattern of growth, such as metaplasia or dysplasia. However, metaplasia or dysplasia does not always progress to neoplasia. The word is from Ancient Greek νέος- "neo" "new" and πλάσμα "plasma" "formation, creation".

Intraductal papillary mucinous neoplasm (IPMN) is a type of tumor that can occur within the cells of the pancreatic duct. IPMN tumors produce mucus, and this mucus can form pancreatic cysts. Although intraductal papillary mucinous neoplasms are benign tumors, they can progress to pancreatic cancer. As such IPMN is viewed as a precancerous condition. Once an intraductal papillary mucinous neoplasm has been found, the management options include close monitoring and pre-emptive surgery.

A neoplasm can be benign, potentially malignant, or malignant (cancer).

- Benign tumors include uterine fibroids and melanocytic nevi (skin moles). They are circumscribed and localized and do not transform into cancer.

- Potentially-malignant neoplasms include carcinoma in situ. They are localised, do not invade and destroy but in time, may transform into a cancer.

- Malignant neoplasms are commonly called cancer. They invade and destroy the surrounding tissue, may form metastases and, if untreated or unresponsive to treatment, will prove fatal.

- Secondary neoplasm refers to any of a class of cancerous tumor that is either a metastatic offshoot of a primary tumor, or an apparently unrelated tumor that increases in frequency following certain cancer treatments such as chemotherapy or radiotherapy.

- Rarely there can be a metastatic neoplasm with no known site of the primary cancer and this is classed as a cancer of unknown primary origin

Pathologists classify intraductal papillary mucinous neoplasms (IPMNs) into two broad groups - those that are associated with an invasive cancer and those that are not associated with an invasive cancer. This separation has critical prognostic significance. Patients with a surgically resected intraductal papillary mucinous neoplasm without an associated invasive cancer have an excellent prognosis (>95% will be cured), while patients with a surgically resected intraductal papillary mucinous neoplasm with an associated invasive cancer have a worse prognosis. Intraductal papillary mucinous neoplasms without an associated invasive cancer can be further subcategorized into three groups. They are IPMN with low-grade dysplasia, IPMN with moderate dysplasia, and IPMN with high-grade dysplasia. This categorization is less important than the separation of IPMNs with an associated cancer from IPMNs without an associated invasive cancer, but this categorization is useful as IPMNs are believed to progress from low-grade dysplasia to moderate dysplasia to high-grade dysplasia to an IPMN with an associated invasive 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.

Metastatic breast cancer, also referred to as metastases, advanced breast cancer, secondary tumours, secondaries or stage 4 breast cancer, is a stage of breast cancer where the disease has spread to distant sites beyond the axillary lymph nodes. There is no cure for metastatic breast cancer. There is no stage after IV.

It usually occurs several years after the primary breast cancer, although it is sometimes diagnosed at the same time as the primary breast cancer or, rarely, before the primary breast cancer has been diagnosed.

Metastatic breast cancer cells frequently differ from the preceding primary breast cancer in properties such as receptor status. The cells have often developed resistance to several lines of previous treatment and have acquired special properties that permit them to metastasize to distant sites. Metastatic breast cancer can be treated, sometimes for many years, but it cannot be cured. Distant metastases are the cause of about 90% of deaths due to breast cancer.

Breast cancer can metastasize anywhere in body but primarily metastasizes to the bone, lungs, regional lymph nodes, liver and brain, with the most common site being the bone. Treatment of metastatic breast cancer depends on location of the metastatic tumours and includes surgery, radiation, chemotherapy, biological, and hormonal therapy.

Typical environmental barriers in a metastatic event include physical (a basement membrane), chemical (reactive oxygen species or ROS, hypoxia and low pH) and biological (immune surveillance, inhibitory cytokines and regulatory extra-cellular matrix (ECM) peptides) components. Organ-specific anatomic considerations also influence metastasis; these include blood-flow patterns from the primary tumor and the homing ability of cancer cells to certain tissues. The targeting by cancer cells of specific organs is probably regulated by chemo-attractant factors and adhesion molecules produced by the target organ, along with cell-surface receptors expressed by the tumor cells.

Breast cancer is cancer that develops from breast tissue. Signs of breast cancer may include a lump in the breast, a change in breast shape, dimpling of the skin, fluid coming from the nipple, or a red scaly patch of skin. In those with distant spread of the disease, there may be bone pain, swollen lymph nodes, shortness of breath, or yellow skin.

Risk factors for developing breast cancer include being female, obesity, lack of physical exercise, drinking alcohol, hormone replacement therapy during menopause, ionizing radiation, early age at first menstruation, having children late or not at all, older age, and family history. About 5–10% of cases are due to genes inherited from a person's parents, including BRCA1 and BRCA2 among others. Breast cancer most commonly develops in cells from the lining of milk ducts and the lobules that supply the ducts with milk. Cancers developing from the ducts are known as ductal carcinomas, while those developing from lobules are known as lobular carcinomas. In addition, there are more than 18 other sub-types of breast cancer. Some cancers, such as ductal carcinoma in situ, develop from pre-invasive lesions. The diagnosis of breast cancer is confirmed by taking a biopsy of the concerning lump. Once the diagnosis is made, further tests are done to determine if the cancer has spread beyond the breast and which treatments it may respond to.

The balance of benefits versus harms of breast cancer screening is controversial. A 2013 Cochrane review stated that it is unclear if mammographic screening does more good or harm. A 2009 review for the US Preventive Services Task Force found evidence of benefit in those 40 to 70 years of age, and the organization recommends screening every two years in women 50 to 74 years old. The medications tamoxifen or raloxifene may be used in an effort to prevent breast cancer in those who are at high risk of developing it. Surgical removal of both breasts is another preventative measure in some high risk women. In those who have been diagnosed with cancer, a number of treatments may be used, including surgery, radiation therapy, chemotherapy, hormonal therapy and targeted therapy. Types of surgery vary from breast-conserving surgery to mastectomy. Breast reconstruction may take place at the time of surgery or at a later date. In those in whom the cancer has spread to other parts of the body, treatments are mostly aimed at improving quality of life and comfort.

Outcomes for breast cancer vary depending on the cancer type, extent of disease, and person's age. Survival rates in the developed world are high, with between 80% and 90% of those in England and the United States alive for at least 5 years. In developing countries survival rates are poorer. Worldwide, breast cancer is the leading type of cancer in women, accounting for 25% of all cases. In 2012 it resulted in 1.68 million new cases and 522,000 deaths. It is more common in developed countries and is more than 100 times more common in women than in men.

Hereditary breast–ovarian cancer syndromes (HBOC) are cancer syndromes that produce higher than normal levels of breast cancer and ovarian cancer in genetically related families (either one individual had both, or several individuals in the pedigree had one or the other disease). The hereditary factors may be proven or suspected to cause the pattern of breast and ovarian cancer occurrences in the family.

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.

Triple-negative breast cancers (TNBC) are sometimes classified into "basal-type" and other cancers; however, there is no standard classification scheme. Basal type cancers are frequently defined by cytokeratin 5/6 and EGFR staining. However, no clear criteria or cutoff values have been standardized yet. About 75% of basal-type breast cancers are triple negative.

Some TNBC overexpress epidermal growth factor receptor (EGFR) or transmembrane glycoprotein NMB (GPNMB).

Upon histologic examination, triple-negative breast tumors mostly fall into the categories of "secretory cell carcinoma" or "adenoid cystic types" (both considered less aggressive); "medullary cancers" and grade 3 invasive "ductal carcinomas" with no specific subtype; and highly aggressive "metastatic cancers". Medullary TNBC in younger women are frequently "BRCA1"-related.

Rare forms of triple-negative breast cancer are "apocrine" and "squamous carcinoma". "Inflammatory breast cancer" is also frequently triple negative.

Many proteins such as Caveolin 1/2, Survivin are researched as possible classification or prognostic factors.

TNBCs have been classified using an integrative analysis of cancer genomics data (DNA copy number, DNA methylation, and mRNA) and PPI data from a prognostic point of view and several key subnetworks (i.e. ubiquitin/proteasome, complement system, metabolism-related Warburg effect, ER-Golgi-cell surface trafficking, transcription) significantly related to patient survival have been identified.

A gonadal tissue neoplasm is a tumor having any histology characteristic of cells or tissues giving rise to the gonads. These tissues arise from the sex cord and stromal cells. The tumor may be derived from these tissues, or produce them.

Although the tumor is composed of gonadal tissue, it is not necessarily located in an ovary or testicle.

A gonadal tissue neoplasm should not be confused with a urogenital neoplasm, though the two topics are often studied together. The embryology of the gonads is only indirectly related to the embryology of the external genitals and urinary system.