Types of Brain Tumors
Brain tumors are classified depending on the exact site of the tumor, the type of tissue involved, whether they are noncancerous (benign) or cancerous (malignant) and other factors. Sometimes, tumors that start out being less invasive can become more invasive. Tumors may occur at any age, but many types of tumors occur most often in a certain age group. In adults, gliomas and meningiomas are most common.
Pediatric brain tumors are diagnosed most often between the ages of three and eight, but can occur at any age. Children with brain tumors are diagnosed and treated by our partner, Ann & Robert H. Lurie Children's Hospital of Chicago's Falk Brain Tumor Center. One of the first institutions in the country to develop a cohesive, multidisciplinary program for brain tumor treatment, Lurie Children's treats over 67 percent of children in the Chicago area who are newly diagnosed with this condition and treat many additional patients with recurrent disease.
Astrocytomas are the most common type of glioma and begin in cells called astrocytes in the cerebrum or cerebellum. There are four types of astrocytoma: anaplastic astrocytoma, glioblastoma multiforme, low-grade astrocytoma and pilocytic astrocytoma.
Anaplastic astrocytoma, a tumor that begins in the brain or spinal cord in small, star-shaped cells called astrocytes, is a malignant tumor that can quickly grow and spread to nearby tissues. It accounts for about 3 percent of all brain tumors. Anaplastic astrocytomas are also known as Malignant Gliomas and Grade 3 Gliomas.
Glioblastoma multiforme is the most common and aggressive form of astrocytoma that accounts for about 20 percent of all brain tumors. These tumors tend to penetrate throughout the area of the brain where the tumor is located, making their treatment more complicated. Glioblastomas are the most aggressive brain tumors, sometimes starting out as fast growing tumors and sometimes developing from slow-growing tumors that become more and more aggressive over many years.
Low-grade astrocytoma is a slow-growing tumor that can often spread into nearby tissue and can become a higher grade if untreated. It accounts for about 11 percent of all brain tumors.
Pilocytic astrocytoma is a slow-growing tumor that is most often benign and rarely spreads into nearby tissue. It accounts for about 2 percent of all brain tumors.
Brain Stem Gliomas
The most common type of brainstem glioma is an astrocytoma. Like astrocytomas elsewhere in the brain, they can be slow growing or fast growing. Brain stem gliomas are also called cerebellar gliomas.
The brainstem is a small but essential part of the brain that controls many of our motor and sensory functions. Many nerves that control the eyes, face and throat also come from the brainstem. It is also the part of the brain that controls many of our automatic functions such as heart rate and breathing. A tumor in the brainstem can affect any of these functions, depending on where it is located. Common symptoms that brainstem gliomas cause are double vision, trouble swallowing, facial weakness or weakness of the left or right side.
These benign brain tumors occur at the base of the brain called the sellar region, near the pituitary gland. Symptoms may include headaches due to increased intracranial pressure, vision problems and/or hormonal imbalances, which can result in short stature. Although these tumors are benign, they are difficult to remove due to the sensitive brain structures that surround them.
This is a type of brain tumor that begins in cells lining the spinal cord central canal (fluid-filled space down the center) or the ventricles (fluid-filled spaces of the brain). Ependymomas may also form in the choroid plexus (tissue in the ventricles that makes cerebrospinal fluid). They are also called ependymal tumors.
The germinoma is the most common type of germ cell tumor of the brain. It typically occurs in the pineal or suprasellar region of the brain. Because it tends to spread via the cerebrospinal fluid, diagnosis includes evaluation of the entire brain and spinal cord. Surgery for germinoma depends on its accessibility and position relative to critical brain structures. Chemotherapy and radiation can also be effective treatments for some patients.
These pediatric brain tumors are classified as PNETs (see Primitive Neuroectodermal Tumors) and are found near the midline of the cerebellum. Even though they are classified as pediatric tumors, they can be found in teens and young adults, too. These tumors grow rapidly and often block drainage of the cerebral spinal fluid, causing symptoms associated with increased intracranial pressure. Medulloblastoma cells can spread (metastasize) to other areas of the central nervous system, especially around the spinal cord. The typical treatment plan includes a combination of surgery, radiation and chemotherapy, depending upon the age of the patient.
Most meningiomas are considered nonmalignant or low-grade tumors. However, unlike nonmalignant tumors elsewhere in the body, some of these brain tumors can cause disability and may sometimes be life threatening. In many cases, meningiomas grow slowly. Other meningiomas grow more rapidly or have sudden growth spurts. There is no way to predict the rate of growth of a meningioma or to be certain how long a specific tumor was growing before diagnosis.
Metastatic Brain Tumors
A metastatic, or secondary, brain tumor is one that begins as cancer in another part of the body. Some of the cancer cells may be carried to the brain by the blood or lymphatic fluid or may spread from adjacent tissue. There has been an increase in metastatic lesions, the most common brain tumors, as people are surviving primary cancers for longer periods of time.The site where the cancerous cells originated is referred to as the primary cancer. The primary cancer is usually in the lung, breast, colon, kidney or skin (melanoma), but can originate in any part of the body.
A mixed glioma is often a combination of an astrocytoma and an oligodendroglioma. Mixed gliomas are generally treated for the most anaplastic (cancerous) type of cell found in the tumor.
The term phakomatoses refers to a broad group of neurologic (brain, spine and peripheral nerve) disorders that are also known as neurocutaneous syndromes. These diseases, which affect males and females equally, are lifelong conditions that can cause tumors to grow inside the brain, spinal cord, organs, skin and skeletal bones. The three most common types of neurocutaneous syndromes include the following:
- Tuberous sclerosis: Growths, called tubers, are often found growing inside of the brain and retinal area of the eye. Tuberous sclerosis affects many organs in the body including the brain, spinal cord, lungs, heart, kidneys, skin and skeletal bones.
- Neurofibromatosis (NF): There are two distinct types of NF, classified as NF I and NF II.
- Neurofibromatosis Type I: This is the more common of the two disorders. It is also called Von Recklinghausen's disease. The classic symptom of NF I is light brown patches of pigment on the skin, called cafe-au-lait spots. There is a high rate of brain tumors in patients associated with NF.
- Neurofibromatosis Type II: This type of neurofibromatosis, also known as bilateral acoustic neurofibromatosis, accounts for 2 to 5 percent of cases. This disease is characterized by tumors on the eighth cranial nerve, which can lead to hearing loss, headaches, problems with facial movements, problems with balance and difficulty walking. Other clinical signs of NF II may include seizures, neurofibromas (skin nodules) and cafe-au-lait spots (although this is not as common as in NF I).
- Sturge-Weber Disease: The classic symptom of this disease is a port-wine stain located on the face, typically near or around the eye and forehead areas. A port-wine stain is present from birth and is a flat area that varies in color from red to dark purple. The birthmark is caused by the formation of too many tiny blood vessels under the skin. There may also be associated brain abnormalities on the same side of the brain as the face lesion. Neurological changes that occur with this condition may include seizures, muscle weakness, changes in vision and mental retardation.
This is a rare, slow-growing tumor that begins in oligodendrocytes (cells that cover and protect nerve cells in the brain and spinal cord). It’s also called an oligodendroglial tumor.
Optic Nerve Gliomas
Optic gliomas can affect one or both of the optic nerves, which carry visual information to the brain from each eye. They may also affect the optic chiasm, the area where the optic nerves cross each other in front of the hypothalamus of the brain.
Pinneal Region Tumors
Pineal tumors arise in the region of the pineal gland, a small structure deep within the brain. This gland is thought to be involved in the sleep-wake cycle, though its exact function remains unclear. There are at least 17 types of tumors that may occur in this region, ranging from more aggressive gliomas to benign cysts. The three most common categories of pineal region tumors are gliomas, germ cell tumors (germinomas, embryonal cell carcinoma, teratomas) and pineal cell tumors (pineocytoma and pineoblastoma). Others include meningioma, lymphoma, metastatic tumors and pineal cysts.
The pituitary gland produces hormones that affect growth and the functions of other glands in the body. Certain pituitary tumors secrete abnormally high amounts of their respective hormones and cause related symptoms.
Other pituitary tumors do not secrete hormones, but grow and compress brain tissue, causing other symptoms. For example, due to the proximity of the pituitary gland to the optic nerves, pituitary tumor patients may experience vision problems. Consequently, these tumors are often best treated by a team approach that may include a neurosurgeon, endoscopic surgeon, endocrinologist and/or ophthalmologist. Tumors that occur in this gland are also called adenomas.
Primary Central Nervous System Lymphoma
Primary central nervous system (CNS) lymphoma is a malignant tumor derived from white blood cells localized to the brain. These tumors are rare. However, the incidence of these tumors is rising relative to other brain lesions. This is in part due to the occurrence of primary lymphoma in AIDS and transplant patients.
The most common locations for CNS are the frontal lobes and regions around the ventricles of the brain. Primary CNS lymphoma is usually present in those with severe immunosuppression — commonly in those with AIDS — and represents around 20 percent of all cases of lymphomas in HIV infection. It is also highly associated with Epstein-Barr virus infection in immunodeficient patients.
Primitive Neuroectodermal Tumors (PNET)
There are several tumor types in this category. Names of specific PNETs may be based on the tumor location and include pineoblastoma (located in the pineal region, a form of pineal tumor), medulloblastoma (located in the cerebellum) and cerebral cortex PNET (located in the cerebral cortex). PNET symptoms vary depending on the location, but typically the patient experiences increased intracranial pressure and seizures.
Also known as vestibular schwannoma, neurilemmoma and acoustic neuroma, these benign tumors can occur in the brain or in the spine. They arise from supporting cells of cranial nerves and are most common on the nerves that control hearing and balance. When schwannomas involve these nerves, they are called vestibular schwannomas or acoustic neuromas. Commonly, they present with loss of hearing and occasionally with loss of balance or problems with weakness on one side of the face.