Benign and borderline variants of this neoplasm are rare, and most cases are malignant.

These tumors may have a worse prognosis than serous tumors.

This tumor only affects the outer 1/3 to 1/2 of the external auditory canal as a primary site. If this area is not involved, the diagnosis should be questioned. The most common tumor type is ceruminous adenoid cystic carcinoma and ceruminous adenocarcinoma, NOS.

Pain is the most common symptom, followed by either sensorineural or conductive hearing loss, tinnitus or drainage (discharge). A mass lesion may be present, but it is often slow growing.

Typically, they are cystic neoplasms with polypoid masses that protrude into the cyst. On microscopic pathological examination, they are composed of cells with clear cytoplasm (that contains glycogen) and "hob nail" cells (from which the glycogen has been secreted). The pattern may be glandular, papillary or solid.

A transmissible cancer is a cancer cell or cluster of cancer cells that can be transferred between individuals without the involvement of an infectious agent, such as an oncovirus. Transmission of cancer between humans is rare.

Contagious cancers occur in dogs, Tasmanian devils, Syrian hamsters, and some marine bivalves including soft-shell clams. These cancers have a relatively stable genome as they are transmitted.

In humans, a significant fraction of Kaposi's sarcoma occurring after transplantation may be due to tumorous outgrowth of donor cells. Although Kaposi's sarcoma is caused by a virus (Kaposi's sarcoma-associated herpesvirus), in these cases, it appears likely that transmission of virus-infected tumor cells—rather than the free virus—caused tumors in the transplant recipients.

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.

Sebaceous carcinoma is an uncommon and aggressive malignant cutaneous tumor. Most are typically about 10 mm in size at presentation. This neoplasm is thought to arise from sebaceous glands in the skin and, therefore, may originate anywhere in the body where these glands are found. Because the periocular region is rich in this type of gland, this region is a common site of origin. The cause of these lesions are, in the vast majority of cases, unknown. Occasional cases may be associated with Muir-Torre syndrome.

This type of cancer usually has a poor prognosis because of a high rate of metastasis.

Solid pseudopapillary tumours are typically round, well-demarcated, measuring 2–17 cm in diameter (average 8 cm), with solid and cystic areas with hemorrhage on cut sections.

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".

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).

A solid pseudopapillary tumour (also known as solid pseudopapillary neoplasm or, more formally, solid pseudopapillary tumour/neoplasm of the pancreas) is a low-grade malignant neoplasm of the pancreas of architecture that typically afflicts young women.

Glandular and epithelial neoplasm is a grouping of tumors arising from the glands and epithelium.

An example is adenoma.

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

Squamous epithelial cells are not found in normal thyroid, thus the origin of SCTC is not clear. However, it might be a derived from the embryonic remnants such as thyroglossal duct or branchial clefts. Often SCTC is diagnosed in one of the thyroid lobes, but not in the pyramidal lobe. Another possible way of SCTC development can be through the squamous metaplasia of cells. However, that theory is also controversial, since the Hashimoto's thyroiditis and chronic lymphocytic thyroiditis (neoplasms to be showed squamous metaplasia) are not associated with SCTC. Primary STCT is usually diagnosed in both lobes of thyroid gland. The histopathology of STCT shows a squamous differentiation of tumor cells.

Cystadenocarcinoma is a malignant form of a cystadenoma and is a malignant neoplasm derived from glandular epithelium, in which cystic accumulations of retained secretions are formed. The neoplastic cells manifest varying degrees of anaplasia and invasiveness, and local extension and metastases occur. Cystadenocarcinomas develop frequently in the ovaries, where pseudomucinous and serous types are recognized. Similar tumor histology has also been reported in the pancreas, although it is a considerably rarer entity.

It is the most common malignant ovarian tumor. Contains complex multi-loculated cyst but with exuberant solid areas in places. It usually presents with omental metastases which cause ascites.

An odontogenic tumor is a neoplasm of the cells or tissues that initiate odontogenic processes.

Examples include:

- Adenomatoid odontogenic tumor

- Ameloblastoma, a type of odontogenic tumor involving ameloblasts

- Calcifying epithelial odontogenic tumor

- Keratocystic odontogenic tumor

- Odontogenic myxoma

- Odontoma

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)

The SCTC is biologically aggressive malignant neoplasm which is associated with rapid growth of neck mass followed by infiltration of thyroid-adjacent structures.

Patients usually demonstrate the dysphagia, dyspnea, and voice changes, as well as local pain in the neck.

Poorly differentiated thyroid carcinoma (PDTC) is malignant neoplasm of follicular cell origin showing intermediate histopathological patterns between differentiated and undifferentiated thyroid cancers.

A mammary tumor is a neoplasm originating in the mammary gland. It is a common finding in older female dogs and cats that are not spayed, but they are found in other animals as well. The mammary glands in dogs and cats are associated with their nipples and extend from the underside of the chest to the groin on both sides of the midline. There are many differences between mammary tumors in animals and breast cancer in humans, including tumor type, malignancy, and treatment options. The prevalence in dogs is about three times that of women. In dogs, mammary tumors are the second most common tumor (after skin tumors) over all and the most common tumor in female dogs with a reported incidence of 3.4%. Multiple studies have documented that spaying female dogs when young greatly decreases their risk of developing mammary neoplasia when aged. Compared with female dogs left intact, those spayed before puberty have 0.5% of the risk, those spayed after one estrous cycle have 8.0% of the risk, and dogs spayed after two estrous cycles have 26.0% of the risk of developing mammary neoplasia later in life. Overall, unspayed female dogs have a seven times greater risk of developing mammary neoplasia than do those that are spayed. While the benefit of spaying decreases with each estrous cycle, some benefit has been demonstrated in female dogs even up to 9 years of age. There is a much lower risk (about 1 percent) in male dogs and a risk in cats about half that of dogs.

A myxoid liposarcoma is a malignant adipose tissue neoplasm of myxoid appearance histologically.

Myxoid liposarcomas are the second most common type of liposarcoma, representing 30–40% of all liposarcomas in the limbs; occurring most commonly in the legs, particularly the thigh, followed by the buttocks, retroperitoneum, trunk, ankle, proximal limb girdle, head and neck, and wrist. They occur in the intermuscular fascial planes or deep-seated areas. They present as a large, slow-growing, painless mass.

They are associated with a fusion between DDIT3 or "CHOP" (at 12q13.1-q13.2) and FUS or "TLS" (at 16p11.2) or EWS (at 22q12.2).

The specific translocation of FUS-DDIT3 is t(12;16)(q13;p11).

The treatment is simple excision and exclusion of a malignant neoplasm.

The exact causes for the development of canine mammary tumors are not fully understood. However, hormones of the estrous cycle seem to be involved. Female dogs who are not spayed or who are spayed later than the first heat cycle are more likely to develop mammary tumors. Dogs have an overall reported incidence of mammary tumors of 3.4 percent. Dogs spayed before their first heat have 0.5 percent of this risk, and dogs spayed after just one heat cycle have 8 percent of this risk. The tumors are often multiple. The average age of dogs with mammary tumors is ten to eleven years old. Obesity at one year of age and eating red meat have also been associated with an increased risk for these tumors, as has the feeding of high fat homemade diets.

There are several hypotheses on the molecular mechanisms involved in the development of canine mammary tumors but a specific genetic mutation has not been identified.

Well-differentiated and moderately differentiated sebaceous carcinoma tend to exhibit vacuolization within the cytoplasm of the tumor cells. Histology may mimic basal cell carcinoma.

Children affected by pilocytic astrocytoma can present with different symptoms that might include failure to thrive (lack of appropriate weight gain/ weight loss), headache, nausea, vomiting, irritability, torticollis (tilt neck or wry neck) difficulty to coordinate movements and visual complaints (including nystagmus). The complaints may vary depending on the location and size of the neoplasm. The most common symptoms are associated with increased intracranial pressure due to the size of the neoplasm.