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.

Patients typically present with swelling with or without pain. The slow-growing tumor predominantly arises in long bones in a subcortical location (95% in the tibia or fibula). Most commonly, patients are in their second or third decade, but adamantinoma can occur over a wide age range.

Benign osteofibrous dysplasia may be a precursor of adamantinoma or a regressive phase of adamantinoma.

Histologically, islands of epithelial cells are found in a fibrous stroma. The tumor is typically well-demarcated, osteolytic and eccentric, with cystic zones resembling soap bubbles.

Pilocytic astrocytoma or juvenile pilocytic astrocytoma or cystic cerebellar astrocytoma (and its variant juvenile pilomyxoid astrocytoma) is a brain tumor that occurs more often in children and young adults (in the first 20 years of life). They usually arise in the cerebellum, near the brainstem, in the hypothalamic region, or the optic chiasm, but they may occur in any area where astrocytes are present, including the cerebral hemispheres and the spinal cord. These tumors are usually slow growing and benign. The neoplasms are associated with the formation of a single (or multiple) cyst(s), and can become very large.

Pilocytic astrocytomas are often cystic, and, if solid, tend to be well-circumscribed. It is characteristically easily seen on Computed tomography (CT scans) and Magnetic Resonance Imaging (MRI).

Juvenile pilocytic astrocytoma is associated with neurofibromatosis type 1 (NF1), and optic gliomas are among the most frequently encountered tumors in patients with this disorder. The majority of pilocytic astrocytomas have a unique KIAA1549-BRAF fusion gene.

Adamantinoma (from the Greek word "adamantinos", meaning "very hard") is a rare bone cancer, making up less than 1% of all bone cancers. It almost always occurs in the bones of the lower leg and involves both epithelial and osteofibrous tissue.

The condition was first described by Fischer in 1913.

A nervous system neoplasm is a tumor affecting the nervous system. Types include:

- Nerve sheath tumor

- Brain tumor

- Arachnoid cyst

- Optic nerve glioma

The signs and symptoms of brain tumors are broad. People with brain tumors will experience them no matter if the tumor is benign (not cancerous) or cancerous. Primary and secondary brain tumors present with similar symptoms, depending on the location, size, and rate of growth of the tumor. For example, larger tumors in the frontal lobe can cause changes in the ability to think. However, a smaller tumor in an area such as Wernicke's area (small area responsible for language comprehension) can result in a greater loss of function.

Headaches as a result of raised intracranial pressure can be an early symptom of brain cancer. However, isolated headache without other symptoms is rarer, and other symptoms often occur before headaches become common. Certain warning signs for headache exist which make it more likely to be associated with brain cancer. These are as defined by the American Academy of Neurology: "abnormal neurological examination, headache worsened by Valsalva maneuver, headache causing awakening from sleep, new headache in the older population, progressively worsening headache, atypical headache features, or patients who do not fulfill the strict definition of migraine".

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.

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.

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".

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 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

Malignant transformation to squamous cell carcinoma may occur, but is unusual.

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.

Swelling is the most common presenting complaint; however, OKCs may be asymptomatic and found incidentally on dental X-rays.

Vascular tissue neoplasms, like neoplasms of all tissues, are classified to benign and malignant ones, according to their biological behavior.

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

An example is adenoma.

Most malignant vascular tumors are considered sarcomas, a major histological group of tumors, arising from transformed cells of mesenchymal origin.

- Hemangiosarcoma

- Hemangiopericytoma

- Kaposi's Sarcoma

- Hemangioblastoma

- Lymphangiosarcoma

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.

Congenital mesoblastic nephroma typically (76% of cases) presents as an abdominal mass which is detected prenatally (16% of cases) by ultrasound or by clinical inspection (84% of cases) either at birth or by 3.8 years of age (median age ~1 month). The neoplasm shows a slight male preference. Concurrent findings include hypertension (19% of cases), polyhydramnios (i.e. excess of amniotic fluid in the amniotic sac) (15%), hematuria (11%), hypercalcemia (4%), and elevated serum levels of the kidney-secreted, hypertension-inducing enzyme, renin (1%). Congenital anomalies have been reported in 11 patients: 6 with genitourinary anomalies, 2 with gastrointestinal anomalies, 1 with hydrocephalus, and 1 with the Beckwith–Wiedemann syndrome. The vast majority of patients present with localized (i.e. non-metastatic) disease. Most patients' disease is classified at presentation as stage I or II (i.e. localized), few patients present with stage III (i.e. locally advanced/infiltrating), and virtually no patients present with stage IV (metastases present or V (i.e. tumors in both kidneys) disease (see staging of renal cancer).

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.

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.

An muscle tissue neoplasm is a neoplasm derived from muscle.

An example is myoma.

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".

An adipose tissue neoplasm is a neoplasm derived from adipose tissue.

An example is lipoma.