According to a Dutch source juvenile pilocytic astrocytoma occurs at a rate of 2 in 100,000 people. Most affected are children ages 5–14 years. According to the National Cancer Institute more than 80% of astrocytomas located in the cerebellum are low grade (pilocytic grade I) and often cystic; most of the remainder are diffuse grade II astrocytomas.

Tumors of the optic pathway account for 3.6-6% of pediatric brain tumors, 60% of which are juvenile pilocytic astrocytomas. Astrocytomas account for 50% of pediatric primary central nervous system tumors. About 80-85% of cerebellar astrocytomas are juvenile pilocytic astrocytomas.

Recent genetic studies of pilocytic astrocytomas show that some sporadic cases have gain in chromosome 7q34 involving the BRAF locus.

In reported cases of the tumor over the last 25 years, the number of affected females with astroblastoma is significantly higher than the number of affected males. Sughrue et al. confirmed this trend, stating that 70% of the cases with clearly stated gender were female (100 cases total). While several publications support a genetic predisposition to females, the underlying reasons are still unknown.

At this point, no literature has indicated whether environmental factors increase the likelihood of astroblastoma. Although cancer in general is caused by a variety of external factors, including carcinogens, dangerous chemicals, and viral infections, astroblastoma research has not even attempted to classify incidence in this regard. The next few decades will aid in this understanding.

Grade I pilocytic astrocytoma and cerebellar gliomas are not associated with recurrence after complete resection. Grade II astrocytomas and cerebellar gliomas are more likely to recur after surgical removal. Pilomyxoid astrocytomas may behave more aggressively than classic pilocytic astrocytoma.

After complete surgical removal, in cases of progressive/recurrent disease or when maximal surgical removal has been achieved, chemotherapy and/or radiation therapy will be considered by the medical team.

After complete surgical removal, a SEGA tumor does not grow back. They do not metastasize to other parts of the body. However, the patient is still at risk for, and often develops, new tumors arising from subependymal nodules elsewhere in the ventricular system.

Subependymal giant cell astrocytoma (SEGA, SGCA, or SGCT) is a low-grade astrocytic brain tumor (astrocytoma) that arises within the ventricles of the brain. It is most commonly associated with tuberous sclerosis complex (TSC). Although it is a low-grade tumor, its location can potentially obstruct the ventricles and lead to hydrocephalus.

Brain, other CNS or intracranial tumors are the ninth most common cancer in the UK (around 10,600 people were diagnosed in 2013), and it is the eighth most common cause of cancer death (around 5,200 people died in 2012).

Its presence is associated with either pilocytic astrocytoma (more common) or Alexander's disease (a rare leukodystrophy). They are also seen in the context of fucosidosis.

Pilocytic astrocytoma is the most common primitive tumor in pediatric patients.

Epidemiological studies are required to determine risk factors. Aside from exposure to vinyl chloride or ionizing radiation, there are no known environmental factors associated with brain tumors. Mutations and deletions of so-called tumor suppressor genes, such as P53, are thought to be the cause of some forms of brain tumor. Inherited conditions, such as Von Hippel–Lindau disease, multiple endocrine neoplasia, and neurofibromatosis type 2 carry a high risk for the development of brain tumors. People with celiac disease have a slightly increased risk of developing brain tumors.

Although studies have not shown any link between cell phone or mobile phone radiation and the occurrence of brain tumors, the World Health Organization has classified mobile phone radiation on the IARC scale into Group 2B – possibly carcinogenic. Discounting claims that current cell phone usage may cause brain cancer, modern, third-generation (3G) phones emit, on average, about 1% of the energy emitted by the GSM (2G) phones that were in use when epidemiological studies that observed a slight increase in the risk for glioma – a malignant type of brain cancer – among heavy users of wireless and cordless telephones were conducted.

A Rosenthal fiber is a thick, elongated, worm-like or "corkscrew" eosinophilic (pink) bundle that is found on H&E staining of the brain in the presence of long-standing gliosis, occasional tumors, and some metabolic disorders.

Based on a survey of >800, surgical removal of the entire involved kidney plus the peri-renal fat appeared curative for the majority of all types of mesoblastic nephroma; the patient overall survival rate was 94%. Of the 4% of non-survivors, half were due to surgical or chemotherapeutic treatments. Another 4% of these patients suffered relapses, primarily in the local area of surgery rare cases of relapse due to lung or bone metastasis.. About 60% of these recurrent cases had a complete remission following further treatment. Recurrent disease was treated with a second surgery, radiation, and/or chemotherapy that often vincristine and actinomycin treatment. Removal of the entire afflicted kidney plus the peri-renal fat appears critical to avoiding local recurrences. In general, patients who were older than 3 months of age at diagnosis or had the cellular form of the disease, stage III disease, or involvement of renal lymph nodes had a higher recurrence rate. Among patients with these risk factors, only those with lymph node involvement are recommended for further therapy.

It has been suggested that mesoblastic nephroma patients with lymph node involvement or recurrent disease might benefit by adding the ALK inhibitor, crizotinib, or a tyrosine kinase inhibitor, either larotrectinib or entrectinib, to surgical, radiation, and/or chemotherapy treatment regimens. These drugs inhibit NTRK3's tyrosine kinase activity. Crizotinib has proven useful in treating certain cases of acute lymphoblastic leukemia that are associated with the "ETV6-NTRK3" fusion gene while larotrectinib and entrectinib have been useful in treating various cancers (e.g. a metastatic sarcoma, papillary thyroid cancer, non-small-cell lung carcinoma, gastrointestinal stromal tumor, mammary analog secretory carcinoma, and colorectal cancer) that are driven by mutated, overly active tyrosine kinases. Relevant to this issue, a 16-month-old girl with infantile fibrosarcoma harboring the "ETV6–NTRK3" fusion gene was successfully trated with larotrectinib. The success of these drugs, howwever, will likely depend on the relative malignancy-promoting roles of ETV6-NTRK3 protein's tyrosine kinase activity, the lose of ETV6-related transcription activity accompanying formation of ETV6-NTRK3 protein, and the various trisomy chromosomes that populate mesoblastic nephroma.

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

- Nerve sheath tumor

- Brain tumor

- Arachnoid cyst

- Optic nerve glioma

SCTC exhibits a highly aggressive phenotype, thus prognosis of that malignancy is extremely poor. The overall survival is less than 1 year in most of cases.

A germinoma is a type of germ cell tumor, which is not differentiated upon examination. It may be benign or malignant.

The prognosis for individuals with TSC depends on the severity of symptoms, which range from mild skin abnormalities to varying degrees of learning disabilities and epilepsy to severe intellectual disability, uncontrollable seizures, and kidney failure. Those individuals with mild symptoms generally do well and live long, productive lives, while individuals with the more severe form may have serious disabilities. However, with appropriate medical care, most individuals with the disorder can look forward to normal life expectancy.

A study of 30 TSC patients in Egypt found, "...earlier age of seizures commencement (<6 months) is associated with poor seizure outcome and poor intellectual capabilities. Infantile spasms and severely epileptogenic EEG patterns are related to the poor seizure outcome, poor intellectual capabilities and autistic behavior. Higher tubers numbers is associated with poor seizure outcome and autistic behavior. Left-sided tuber burden is associated with poor intellect, while frontal location is more encountered in ASD. So, close follow up for the mental development and early control of seizures are recommended in a trial to reduce the risk factors of poor outcome. Also early diagnosis of autism will allow for earlier treatment and the potential for better outcome for children with TSC."

Leading causes of death include renal disease, brain tumour, lymphangioleiomyomatosis of the lung, and status epilepticus or bronchopneumonia in those with severe mental handicap. Cardiac failure due to rhabdomyomas is a risk in the fetus or neonate, but is rarely a problem subsequently. Kidney complications such as angiomyolipoma and cysts are common, and more frequent in females than males and in "TSC2" than "TSC1". Renal cell carcinoma is uncommon. Lymphangioleiomyomatosis is only a risk for females with angiomyolipomas. In the brain, the subependymal nodules occasionally degenerate to subependymal giant cell astrocytomas. These may block the circulation of cerebrospinal fluid around the brain, leading to hydrocephalus.

Detection of the disease should be followed by genetic counselling. It is also important to realise that though the disease does not have a cure, symptoms can be treated symptomatically. Hence, awareness regarding different organ manifestations of TSC is important.

Dysgerminoma is the most common type of malignant germ cell ovarian cancer. Dysgerminoma usually occurs in adolescence and early adult life; about 5% occur in pre-pubertal children. Dysgerminoma is extremely rare after age 50. Dysgerminoma occurs in both ovaries in 10% of patients and, in a further 10%, there is microscopic tumor in the other ovary.

Seminoma is the second most common testicular cancer; the most common is mixed, which may contain seminoma.

Abnormal gonads (due to gonadal dysgenesis and androgen insensitivity syndrome) have a high risk of developing a dysgerminoma. Most dysgerminomas are associated with elevated serum lactic dehydrogenase (LDH), which is sometimes used as a tumor marker.

Metastases are most often present in the lymph nodes.

Most treatments involve some combination of surgery and chemotherapy. Treatment with cisplatin, etoposide, and bleomycin has been described.

Before modern chemotherapy, this type of neoplasm was highly lethal, but the prognosis has significantly improved since.

When endodermal sinus tumors are treated promptly with surgery and chemotherapy, fatal outcomes are exceedingly rare.

Endodermal sinus tumor (EST), also known as yolk sac tumor (YST), is a member of the germ cell tumor group of cancers. It is the most common testicular tumor in children under 3, and is also known as infantile embryonal carcinoma. This age group has a very good prognosis. In contrast to the pure form typical of infants, adult endodermal sinus tumors are often found in combination with other kinds of germ cell tumor, particularly teratoma and embryonal carcinoma. While pure teratoma is usually benign, endodermal sinus tumor is malignant.

The tumor is rare, affecting adults in the 4th decade most commonly. Patients are usually younger than those who present with a lipoma. There is a slight male predominance. Hibernoma are most commonly identified in the subcutaneous and muscle tissue of the head and neck region (shoulders, neck, scapular), followed by thigh, back, chest, abdomen, and arms. In rare cases hibernoma may arise in bone tissue, however it is an incidental finding.

TSC occurs in all races and ethnic groups, and in both genders. The live-birth prevalence is estimated to be between 10 and 16 cases per 100,000. A 1998 study estimated total population prevalence between about 7 and 12 cases per 100,000, with more than half of these cases undetected. These estimates are significantly higher than those produced by older studies, when TSC was regarded as an extremely rare disease. This is due to the invention of CT and ultrasound scanning having enabled the diagnosis of many nonsymptomatic cases. Prior to this, the diagnosis of TSC was largely restricted to severely affected individuals with Vogt's triad of learning disability, seizures, and facial angiofibroma. The total population prevalence estimates have steadily increased from 1:150,000 in 1956, to 1:100,000 in 1968, to 1:70,000 in 1971, to 1:34,200 in 1984, to the present figure of 1:12,500 in 1998. Whilst still regarded as a rare disease, TSC is common when compared to many other genetic diseases.

Congenital mesoblastic nephroma, while rare, is the most common kidney neoplasm diagnosed in the first three months of life and accounts for 3-5% of all childhood renal neoplasms. This neoplasm is generally non-aggressive and amenable to surgical removal. However, a readily identifiable subset of these kidney tumors has a more malignant potential and is capable of causing life-threatening metastases. Congenital mesoblastic nephroma was first named as such in 1967 but was recognized decades before this as fetal renal hamartoma or leiomyomatous renal hamartoma.

A nerve sheath tumor is a type of tumor of the nervous system (nervous system neoplasm) which is made up primarily of the myelin surrounding nerves.

A peripheral nerve sheath tumor (PNST) is a nerve sheath tumor in the peripheral nervous system. Benign peripheral nerve sheath tumors include schwannomas and neurofibromas.

A malignant peripheral nerve sheath tumor (MPNST) is a cancerous peripheral nerve sheath tumor.

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.

Neoplastic tumors are often heterogeneous and contain more than one type of cell, but their initiation and continued growth is usually dependent on a single population of neoplastic cells. These cells are presumed to be clonal – that is, they are derived from the same cell,

and all carry the same genetic or epigenetic anomaly – evident of clonality. For lymphoid neoplasms, e.g. lymphoma and leukemia, clonality is proven by the amplification of a single rearrangement of their immunoglobulin gene (for B cell lesions) or T cell receptor gene (for T cell lesions). The demonstration of clonality is now considered to be necessary to identify a lymphoid cell proliferation as neoplastic.

It is tempting to define neoplasms as clonal cellular proliferations but the demonstration of clonality is not always possible. Therefore, clonality is not required in the definition of neoplasia.

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