What Is A Tumor?

Why Do Tumors Occur?

How Do Brain Tumors Become Evident?

1. The tumor may block the cerebrospinal fluid pathways or because of its size cause pressure to build up inside the child's head. Symptoms of increased pressure due to hydrocephalus or tumor size include headaches (often in the morning or during sleep), often associated with nausea and vomiting. After vomiting, the child may feel some relief of his/her headache.
2. The tumor has pressed on the surrounding brain, affecting its ability to function properly.

   Symptoms that commonly occur in children, depending on the area of the brain affected, include:

   • unsteady walking
   • changes in eye movements
   • blurred or double vision
   • weakness of arm and leg on one side
   • seizures
   • fatigue or changes in energy level or sleep patterns
   • personality change
   • growth and development patterns may be disturbed (rarely)

How is a Brain Tumor Diagnosed?

What Is Meant By Primary And Secondary Brain Tumors?

What Is Meant By Benign And Malignant Brain Tumors?

Malignant tumors are fast growing since the cells that are found in them divide quickly. These tumors may invade and damage important structures and it is uncommon for primary malignant tumors to be completely removed surgically. Malignant primary brain tumors seldom travel (metastasize) to any other part of the body though they may spread to other parts of the brain or spinal cord.

How Common Are Brain Tumors?

Over 10,000 cases of brain tumors (primary and secondary) occur in Canada every year. At least one third of these cases are primary brain tumors.

Different types of tumors in childhood appear to be related to certain ages. The majority of tumors occur between the ages of 4 and 8.

What Types Of Brain Tumors Are Common In Children?

On occasion, the cells in the tumors may change and the diagnosis may change from one category to another.

This classification system may again change in the future as pathologists, geneticists and biochemists look at things such as glial proteins present in cells, genetics and other markers in making their diagnosis.

The following contains a description of some brain tumors common in children. For more detailed information consult your physician.

• Gliomas

  This is a name given to a family of brain tumors that are formed from the supporting cells of the nervous system. They do not arise from the neurons (nerves). These tumors account for over half of all brain tumors. Gliomas are subclassified into categories according to their cell type.

  Gliomas may be given different names from centre to centre and over the past few years, patients have become increasingly confused when they read literature or speak to someone beyond their primary physician.

  Generally, gliomas are classified according to whether they are slow or fast growing.

• Astrocytomas

  One third of all pediatric brain tumors are astrocytomas.

  Grading Systems for Astrocytic Tumors

  A number of different brain tumor classification systems have been proposed and continue to be used to group brain tumors into subtypes which help predict specific tumor growth characteristics.

  An accurate and reliable classification system used by physicians world-wide would be especially useful in the evaluation of different brain tumor treatments. The use of different classification systems for the same tumor has led to some confusion and it is recommended that you be aware of the type of tumor classification system used in the centre where your child is receiving treatment. The major classification systems used are outlined in the table below. The classification system used in this book is that of the World Health Organization's revised 1993 classification. Pilocytic astrocytoma is clearly differentiated from Astrocytoma (low grade) and the designation anaplastic astrocytoma and glioblastoma multiforme (GBM) are used to denote malignant astrocytic tumors. Please refer to the appendices for a complete schedule of classifications.

  ---

  Comparison of a number of commonly used grading systems for astrocytomas

  World Health            |               |
  Organization            |  Kernohan     |    ..... St. Anne / Mayo Clinic .....
  Designation             |  Grading      |    Designation  Histological Criteria
  ======================= |  ============ |    ===========--=====================
  Pilocytic Astrocytoma   |               |    Astrocytoma  Grade 1 Zero criteria
                          |               | 
  Astrocytoma             |  Astrocytoma  |    Astrocytoma  One criteria usually
  (low grade)             |  Grade 1      |    Grade 2      nuclear atypia
                          |  Astrocytoma  |
                          |  Grade 2      |
                          |               |
  Anaplastic astrocytoma  |  Astrocytoma  |    Astrocytoma  Two criteria usually
                          |  Grade 3      |    Grade 3      nuclear atypia and 
                          |               |                 mitotic activity
                          |               |
  Glioblastoma Multiforme |  Astrocytoma  |    Astrocytoma  Three criteria usually
    (GBM)                 |  Grade 4      |    Grade 4      nuclear atypia,
                          |               |                 mitoses,
                          |               |                 endotherial proliferation
                          |               |                 and/or necrosis
  

  Adapted from Kleihues et al Brain Pathology 3. 255-268 (1993)

  ---

  • Cerebellar Pilocytic Astrocytomas

    These tumors are considered benign. First symptoms of these tumors are usually headache, vomiting or an unsteady gait. They occur equally between the sexes and at all ages in children, although they are unusual in infants. Approximately two-thirds of these tumors are cystic (have a fluid cyst associated with a solid mass) in nature.

    Management of the child with an astrocytoma usually involves also treating the problem of hydrocephalus. This is usually accomplished pre-operatively with steroids (dexamethasone, or the more common trade name of Decadron) which frequently relieve symptoms in 24-48 hours. A second approach to hydrocephalus infrequently requires the placement of a shunt in the days before surgery. See the chapter on shunts.

    The goal of treatment of a cerebellar astrocytoma is complete surgical removal. This is achieved in a large majority of cases, and no further treatment is necessary. If total removal is not possible (for example it may have grown into the brain stem) radiation therapy may be necessary. Chemotherapy has not been found to be useful in the treatment of cerebellar astrocytomas. Pilocytic astrocytomas can occur in other parts of the brain and their treatment is usually surgery and radiation therapy if necessary.

  • Hemispheric Astrocytoma (low grade)

    These are astrocytomas that are located in the hemispheres of the brain. They are most common in children between the ages of 8 and 12 years. First symptoms of these tumors usually include nausea, vomiting, headache and difficulties with vision.

    Surgical removal is the method of treatment for these astrocytomas. Radiation may also be necessary if the tumor is in an area of the brain responsible for such functions as speech, understanding or movement and it cannot be easily surgically removed.

  • Anaplastic Astrocytoma

    The cells of these tumors are moderately fast growing and less well defined than an astrocytoma (low grade). Treatment involves removal of as much tumor as safely possible plus radiation and chemotherapy.

  • Glioblastoma Multiforme (GBM)

    These tumors may contain various cell types, hence the name "multiforme". These tumors are more common in the elderly.

    New data suggests that these tumors may be on the increase in the adult population. Surgery may be performed to remove as much tumor as possible. Radiation and chemotherapy are used to control growth of the tumor. Most of these tumors occur in the front portion of the brain (cerebral hemispheres).

    The cells of these tumors grow quickly, are not well defined, and they may frequently spread throughout the brain.

  • Brain Stem Gliomas

    Brain stem gliomas are astrocytomas that usually start in the pons. Ten to twenty-five percent (10%-25%) of pediatric brain tumors will be brain stem gliomas. These tumors occur equally between sexes and most often occur between the ages of 5-10 years. Brain stem gliomas are located in an area of the brain and spinal cord that is responsible for many vital body functions. These include vision, balance, strength, gagging, coughing and swallowing.

    Because of the location of these tumors, surgery is rarely an option (except for biopsy and draining of cyst). Radiation to the mass is the usual method of treatment. Some centres may add chemotherapy before or after radiation treatment.

  • Optic Nerve Gliomas

    Optic nerve gliomas represent four to six percent (46%) of all pediatric brain tumors. They are located along the optic nerves, the optic chiasm and the hypothalamus. See Eye Signs and Symptoms in Brain Tumors.

    These tumors are usually slow growing (astrocytomas). Symptoms will vary depending on location but may include decreased vision, double vision and papilledema (swelling of the optic nerve). If vision has been lost, surgery may be considered. If visual function remains, there will be careful follow-up with imaging studies done at regular intervals. Radiation therapy may be an option. For tumors that involve the hypothalamus and the third ventricle, there may be signs of hydrocephalus as well as hormone imbalance. Surgical treatment of hydrocephalus may be considered. Some tumors located here respond well to chemotherapy and it may be considered.

  • Oligodendrogliomas

    These tumors are not common in children and are slow growing. The mass usually appears calcified (calcium deposits) on imaging (CT scan or MRI scan) showing that it has been there for many years. These tumors arise from the oligodendroglial cells which make up the myelin that insulates nerve fibres. Symptoms of these tumors may include seizures, headache and vision problems. Treatment usually involves surgical removal along with a course of radiation and/or chemotherapy if sub-totally removed.

  • Ependymomas

    These tumors arise from the cells lining the ventricles (hollow channels) of the brain (most commonly the fourth ventricle). As these tumors grow and fill the ventricle, they obstruct the flow of cerebrospinal fluid (CSF) through the brain. These tumors appear more commonly among younger children. Symptoms of this tumor include headache, nausea, vomiting, balance problems and visual disturbances.

    Hydrocephalus, caused by the blocking of the flow of cerebrospinal fluid, may make shunting necessary. Total surgical removal is not always possible, and treatment often involves radiation therapy and/or chemotherapy.

  • Gangliogliomas

    Gangliogliomas are generally slow growing tumors and may occur anywhere in the brain although the temporal lobe is the most common site. The average age at the time of diagnosis is 12 years. Many children are diagnosed after a long history of seizures that have been difficult to treat. Intellectual and behavioral difficulties may be present. Treatment is usually total removal by surgery.

  • Mixed Gliomas

    You may hear this term used. A tumor may be composed of two or more cell types (as seen under the microscope). The tumor is generally named for the type of glioma cells which grow the fastest.

• Primitive Neuroectodermal Tumors (PNET)

  • Medulloblastoma

    Twenty percent (20%) of all pediatric brain tumors are PNETs. They are most commonly found in the cerebellum and are called medulloblastomas when they occur here. They are most commonly found in the cerebellum. These tumors are twice as common in boys, with diagnosis frequently between the ages of 4 and 8. These tumors are fast growing and symptoms include a short, progressive history of headaches, vomiting, loss of appetite and coordination difficulties. Spread outside of the brain and spinal cord is rare although it may occur. Very often, these tumors have spread within the central nervous system before diagnosis. Spread through the CSF is common (carcinomatous meningitis). The extent of the tumor is often classified according to a staging system. This system is outlined below and is an important consideration when planning appropriate treatment:

    ---

    Stage | Description
    ======  =================================================================
    T1      Tumor is less than 3cm. in diameter and does not go beyond the
            midline of the brain, the roof of the fourth ventricle or the
            cerebellar hemispheres.
    
    T2      Tumor is greater than 3 cm. in diameter and grows into neighboring
            brain or spinal cord, or partly fills the fourth ventricle.
    
    T3a     Tumor grows into two neighboring parts of the brain or spinal cord
            or completely fills in the fourth ventricle producing signs of
            hydrocephalus.
    
    T3b     Tumor grows from the floor of the fourth ventricle or brain stem
            and fills the fourth ventricle, producing signs of hydrocephalus.
    
    T4      Tumor spreads to involve the third ventricle or midbrain or upper
            cervical cord.
    
    M0      No evidence of spread around the brain or to any other part of the
            body
    
    M1      Microscopic tumor cells found in cerebrospinal fluid.
    
    M2      Tumor seeding (separate from primary tumor) found in cerebellum,
            subarachnoid space or in the third or lateral (on either side)
            ventricles.
    
    M3      Tumor seeding (separate from primary tumor) found in spinal
            subarachnoid space.
    
    M4      Tumor spread outside the cerebrospinal system.
    

    Chang CH, Housepian EM, Herbert C Jr.: An operative staging system and a megavoltage radiotherapeutic technique for cerebellar medulloblastomas, Radiology 93: 1351-1359, 1969

    ---

    It is important to be aware of the above stages as they may be discussed with you in terms of treating your child's tumor.

    Treatment almost always involves surgery with the goal of removing all (gross total) or as much as possible (subtotal) of the tumor. Radiation is very effective against this tumor and is generally done to the entire head and spinal cord because of the high possibility of seeding malignant cells by way of the cerebrospinal fluid. Chemotherapy has been shown to be effective. After your child has had his/her tumor staged, the treatment best fitted for his/her tumor will be used. An effective chemotherapy protocol has been developed and although we do not yet know the long-term results of its use, the outlook for this type of tumor has improved dramatically over the last ten years. Shunting may be necessary to treat hydrocephalus caused by the tumor interrupting the pathways of the cerebrospinal fluid.

  • Other Primitive Neuroectodermal Tumors

    • cerebral neuroblastoma (located in hemispheres)
    • ependymoblastoma (arises from ventricles)
    • pineoblastoma (occurs in area of pineal gland)
    The cells of these tumors are generally not alike and they are fast growing. They are found throughout the brain and tend to seed (spread in the spinal fluid). They make up less than five percent (5%) of all pediatric brain tumors. They are treated with complete surgical removal if possible and are followed by radiation and chemotherapy.

• Pineal Region Tumors

  The pineal gland is located centrally in the brain and is an outpouching of the third ventricle. Hydrocephalus is usually a presenting symptom as the cerebrospinal fluid pathway may be blocked. The optic (vision) pathways may also be involved and there may be some double vision. Surgery is sometimes possible or a biopsy may be performed to obtain a diagnosis. Some of these tumors are sensitive to radiation. A shunt may be necessary to treat the hydrocephalus, although hydrocephalus may be initially controlled by the use of steroids. Some germ cell tumors may be treated with chemotherapy.

  There are four categories of pineal region tumors:

  1. Germ cell tumors:
     • fast growing:
       • choriocarcinoma
       • embryonal carcinoma
       • endodermal sinus tumor
     • not as fast growing:
       • germinomas
       [ The first two are unique in that they are the only brain tumors that can be diagnosed by a blood test or lumbar puncture. These tests include plasma beta-human chorionic gonadotropins, melatonin levels and cerebrospinal fluid alpha-fetoproteins. ]

     • slow growing:
       • dermoid cysts
       • epidermoid cysts
       • teratomas

       Dermoid and Epidermoid Cysts

       These cysts develop from congenital tissue (formed before birth). Epidermoid cysts contain keratin, cellular debris and cholesterol. Dermoid cysts contain hair and sebaceous (sweat) glands. These masses occur in central areas of the brain such as the hypothalamic region, the vermis of the cerebellum and the pineal region. The bones of the skull (not involving the brain itself) and the spine may also be involved. These cysts are treated with surgery and complete removal is usually possible.

       Teratomas

       This is a congenital tumor which is made up of elements from the three primary cell layers: Ectoderm (skin and nervous system), Mesoderm (muscle, bone and cartilage) and Endoderm (gut lining). These are the earliest cell types in development. It is most commonly a tumor of the pineal gland or lower spinal cord in the central nervous system, but may be found near the base of the brain near the pituitary gland, or the base of the third ventricle. Treatment is usually surgery.

  2. Pineal cell tumors:
     • fast growing: pinealoblastomas
     • slow growing: Pinealocytomas

     These tumors arise from the actual pineal cells of the pineal gland itself. If the cells are dividing quickly, they are considered pinealoblastomas, whereas those tumors with slow growing cells are called pinealomas.

     Treatment is usually biopsy, or if small, surgical removal. Radiation therapy follows and some centres are using chemotherapy.

  3. Glial cell tumors: Any glial tumor, both slow and fast growing, can be found in the pineal region. These are discussed earlier in this chapter (e.g. astrocytomas).

  4. Miscellaneous tumors: These tumors are almost all slow growing:
     • cysts: accumulation of abnormal fluid enclosed in a lining.
     • meningiomas: a tumor with distinct borders usually causing symptoms by pressure on the neighboring area of the brain (discussed later in this chapter).

• Craniopharyngiomas

  These slow growing tumors account for approximately nine percent (9%) of all pediatric brain tumors and usually occur in children between 5 and 10 years of age. These tumors arise from cells along the pituitary stalk and may grow up and involve the hypothalamus, optic nerve pathways and the third ventricle. These tumors are cystic in nature and slow growing. At diagnosis, children may have signs of increased pressure in the brain (third ventricle blocked), visual loss (either decreased vision or visual field problems) and hormone difficulties (growth delay, thyroid deficiency, sexual delay). Complete removal of this tumor is possible if it is in a favorable location. Otherwise, radiation therapy may be used. All of these children will require long term follow-up by an endocrinologist (a physician who studies the hormone systems of the body) and a neuroopthalmologist. Some of these children will require neuropsychological follow-up. Usually, lifelong hormone replacement is necessary.

• Choroid Plexus Papillomas

  The choroid plexus is an infolding of the lining of the ventricular surface. This surface has many blood vessels. The choroid plexus is involved in the production of most of the cerebrospinal fluid. A child with a choroid plexus papilloma usually has marked hydrocephalus due to obstruction of flow and sometimes an overproduction of cerebrospinal fluid.

  The most common location for this tumor is in the lateral ventricles (the ventricles on either side of the brain). These tumors account for one to three percent (1%-3%) of pediatric brain tumors and are most common in children under the age of 2 years. They make up eight percent (8%) of brain tumors diagnosed in newborn babies.

  These tumors are separated into 2 categories as follows:

  • Papillomas: slow growing (vast majority)

  • Carcinomas: fast growing (rare)

  Treatment for these tumors involves complete surgical resection (removal) for papillomas, whereas carcinomas require surgery, radiation and chemotherapy. On rare occasions, carcinomas may spread to other areas.

• Meningiomas

  This is a rare tumor of childhood. It is usually a benign tumor that grows within the skull but on the outside of the brain. On rare occasions it may grow within the ventricles. Surgical removal may be curative. Radiation may be used if complete removal is impossible, or the tumor is fast growing. Meningiomas are more common in adults, especially in old age.

• Colloid Cysts

  These cysts usually occur in the third ventricle and can cause hydrocephalus. They contain embryonic tissue (tissue formed before birth). Treatment includes surgery and sometimes shunting.

• Chordomas

  These tumors develop from remnants of embryonic tissue. They are slow growing and usually do not produce symptoms until middle age. These tumors can arise in the skull bones at the base of the brain, or in the vertebral bones in the neck or sacrum. Treatment is surgery and radiation therapy.

• Lymphomas

  Lymphomas arise from specialized cells of the lymphatic system and occur both in the brain and spinal cord. The incidence is increased in patients after organ transplantation and patients whose immune system is depressed (e.g. AIDS). These tumors are frequently responsive to steroid medication. Surgery and radiation may be indicated along with chemotherapy.

  Primary brain lymphomas are rare in children, but lymphomas starting elsewhere in the body may spread to the brain or spinal fluid.

• Pituitary Adenomas

  These are tumors of the pituitary gland and can be divided into two groups. The first group shows signs of a space-occupying lesion where the other shows signs of abnormal activity of the gland.
  • Space-occupying lesions (nonfunctioning tumor) - Symptoms of these tumors result from pressure on neighboring structures. They may produce visual disturbances if they compress the visual pathways. Hormone secretion by the pituitary gland can be decreased by compression caused by the growing tumor. This can result in signs of hypopituitarism such as a lack of menstrual periods, reduction of body hair, increased sensitivity to the cold and decreased function of glands stimulated by the pituitary. Treatment is surgical removal and radiation is sometimes used, either alone or in conjunction with surgery.

  • Secreting Pituitary Tumors (functioning tumors) - Pituitary tumors that contain hormone-secreting cells often produce clinical symptoms before tests can actually show enlargement of the pituitary gland.

  • Prolactin Secreting Adenomas - These tumors alter hormones resulting in lack of menstrual periods and infertility in women and impotence in men. Galactorrhea (milk coming from the breasts) can also occur.

  • Growth Hormone Secreting Adenomas - This tumor secretes excessive amounts of growth hormone. In children, giantism results and in adults, acromegaly results. Common features of giantism include rapid growth, joint and muscle tenderness, exercise intolerance and fatigue. In the adult, changes can occur slowly over years. Other conditions that may occur include diabetes mellitus, kidney problems, increased metabolic rate and hypertension (high blood pressure).

  • In young children, hypopituitary function (lack of) can result in decreased overall growth and the child doesn't grow at a normal rate.

  • ACTH (Adrenocorticotropic) Secreting Adenomas - These tumors produce ACTH which stimulates the production of cortisol from the adrenal gland. This overproduction of cortisol impairs the body's response to injury and infection. It can deplete the body's potassium while retaining sodium and water. This tumor may result in a change in the body's fat distribution (Cushingoid appearance).

  Treatment for hormone secreting tumors may consist of surgery, radiation or drug therapy. Drug therapy consists of using a medication that decreases the compound released by a specific tumor (e.g. growth hormone, prolactin, ACTH). Hormone replacement may be required after surgery. For further information on this subject, see the chapter on neuroendocrine function.

• Familial Diseases Associated with Brain Tumors

  Genetic counselling is advised in all of the following conditions. Ask for a referral if one is not offered.

  • Neurofibromatosis

    Sometimes called Von Recklinghausen's Disease.
    • Type 1 - This is a genetically dominant disorder that is passed from one generation to the next. Neurofibromas are slow growing tumors located on or beneath the skin. They may also occur in deeper layers as well as in internal organs. Neurofibromas are composed of tissues from the nervous system, (neuro) and fibrous tissue(fibroma), which form the support structure of the nerve. The skin, bones, endocrine glands and nervous system are sites of congenital abnormality.

      Many types of brain tumors can be associated with neurofibromatosis. Most commonly, these are optic nerve tumors, gliomas in other areas, meningiomas and neurofibromas, especially along the spinal cord. These tumors are usually benign. Surgery and/or radiation therapy is sometimes indicated, when the tumor occurs within the central nervous system (brain and spinal cord).

    • Type 2 - This is different from Type 1 but is also a genetically dominant disorder. It is usually diagnosed by the presence of acoustic neuromas (Schwannomas) on the vestibulo-cochlear nerves on one or both sides of the brain. It usually presents as deafness. Other gliomas may be present. Surgery is often indicated.
    The Neurofibromatosis Society of Ontario,
    923 Annes St.,
    Whitby, Ontario L1N 5K7
    
    (The society serves all of Canada)

    or

    Neurofibromatosis, Inc.
    8855 Annapolis Rd., Suite 110,
    Lanham, MD 20706-2924
    U.S.A.

  • Hippel-Lindau Disease

    This is a genetically dominant disorder that may not be evident until the patient has children of his/her own. Hemangioblastomas, often in the cerebellum, are the most common brain tumors associated with this disease. Hemangioblastomas are seen associated with the retina of the eye and, if not treated, can lead to blindness. Treatment is usually surgery for the brain tumor. Laser coagulation can be used for retinal lesions.

  • Tuberous Sclerosis

    This is a genetically dominant disorder which usually starts with seizures. Tumors associated with it are usually giant cell astrocytomas in the region of the third ventricle, presenting with hydrocephalus. It can cause tumors in organs other than the brain. Treatment includes control of seizures and possibly surgery.
    Tuberous Sclerosis Association of Canada,
    2443 New Wood Dr.
    Oakville, Ontario
    L6H 5Y3

    or

    National Tuberous Sclerosis Foundation
    8000 Corporate Dr.,
    Suite 120,
    Landover, MD 20785
    U.S.A.

• Spinal Cord Tumors

  Tumors which occur in the brain can also occur in the spinal cord, the most common ones being in the glioma family (astrocytomas, ependymomas).
  • Intrinsic - These occur in the substance of the spinal cord and may be invasive. Treatment is surgery and/or radiation.
  • Extrinsic - These occur outside the spinal cord and exert pressure on the cord as they grow. The symptoms of these tumors are related to pressure. These tumors can arise from:
    • dura (meningiomas) or nerves (neurofibromas and Schwannomas) surrounding the spinal cord. These tumors indent the spinal cord like a marble.
    • metastatic deposits from tumors elsewhere in the body. These tumors start in the bone surrounding the spinal cord and may compress the spinal cord from a number of sides.
  Spinal cord tumors frequently present with pain. The pain is usually worse at night and may disturb sleep. At times, the pain may radiate around the chest wall and feel like a grip. Any patient who has had a tumor elsewhere in the body and develops frequent back pain should see his/her doctor.

  Treatment is surgery and/or radiation.

  Spinal Cord and Coverings

Other Tumors

• Neuroblastoma

  This tumor originates from cells known as neural crest cells. These primitive nerve cells are present in the adrenal gland (which sits on top of the kidney) and the sympathetic nervous system which is a chain of nerves that run along the front of the spinal column. A tumor can occur anywhere from the head and neck to the pelvis. The cause of neuroblastoma is unknown and the tumor is usually found in infancy and early childhood. Signs and symptoms vary depending on where the tumor causes pressure.

• Rhabdomyosarcoma

  Rhabdomyosarcoma is a cancer of the connective tissues, specifically the skeletal muscle (the muscle attached to the bone). Cells that form these muscles can grow to become a malignant tumor. Since there is so much skeletal muscle in the body, this kind of tumor can arise almost anywhere including the head, neck and muscular areas around the eyes.

  The extent and location of this disease will determine the required treatment. Radiation and chemotherapy are the usual treatment. Surgery may be an option.

• Arachnoid Cysts

  Arachnoid cysts are congenital in origin and may occur anywhere in the brain. In children, they most commonly arise in the back of the brain and in the region of the third ventricle. They are CSF-filled cysts that are lined with the arachnoid membrane (one of the three meningeal coverings). Some arachnoid cysts are self-contained, while others may be connected by a passageway with the ventricles or subarachnoid space. The entrapped fluid may block the CSF pathways, producing hydrocephalus.

Benign Intracranial Hypertension

This entity may often initially be confused with a brain tumor and/or hydrocephalus. The reasons for this confusion are twofold:

1. The child may complain of headache, blurred or double vision, slight numbness of the face, or dizziness.
2. When the physician looks into the child's eyes, he/she finds evidence of increased pressure or papilledema.

The reasons for this problem are not entirely clear. It is known to occur most often in overweight adolescent girls. The diagnosis is made when a lumbar puncture is performed and the pressure measured (it will be increased significantly). It is very important to treat promptly because the increased pressure can lead to permanent visual loss.

Treatment consists mainly of medication (Diamox) which decreases CSF production and may be supplemented by lumbar punctures to remove CSF until normal pressure is maintained. Lastly, it may be necessary to place a permanent shunt in some children.

Leukemia

The survival rate of children with leukemia is high. Children are treated with a combination of chemotherapy drugs with or without radiation treatment. It will continue for 2 to 3 years depending on age, sex, white blood cell count at diagnosis as well as other variables.

Occasionally, a child at high risk with leukemia may require radiation to the head and spinal cord. Radiation is used because drugs commonly used for chemotherapy cannot get through the blood-brain barrier into the brain and kill tumor cells in this location. Very rarely do some leukemia cells make it into the brain and it is expected that they will be killed by the radiation therapy. Alternately, instead of radiation therapy, sometimes chemotherapy drugs are injected directly into the cerebrospinal fluid, either by lumbar puncture or through an Ommaya reservoir into the lateral ventricle, to help prevent the spread of leukemia into the brain or spinal fluid.

It is possible that the child may form a tumor in the brain from the leukemia cells, or much more commonly, that the cells will grow in the cerebrospinal fluid that circulates in the ventricles and around the brain. This is called carcinomatous meningitis. If a child has previously received radiation therapy, he/she cannot receive it again without significant risk of harming healthy cells. In this case, it is possible that an Ommaya reservoir will be put in place by a neurosurgeon. (See Ommaya Reservoir.). Through this reservoir, chemotherapy can be administered directly into the CSF around and in the brain (and thereby bypassing the blood-brain barrier).

Occasionally, children with leukemia or other solid tumors may develop peculiar lesions involving the brain. An example of this would be an infection with bacteria, fungus or virus. A neurosurgeon may be asked to biopsy such a lesion to help in its diagnosis and treatment.

Comparison of Common Pediatric Brain Tumors

Type of Tumor| Description   | Location    | Signs & Symptoms   | Treatment
_____________|_______________|_____________|____________________|___________________
Astrocytoma, | May be cystic,| Cerebellum  | Headache, vomiting,| 1:Surgery
Cerebellar   | usually slow  |             | double vision,     | 2:Radiation
 Astrocytoma | growing       |             | incoordination,    |   if not completely
             |               |             | balance problems   |   removed
             |               |             |                    | 3:Shunting may
             |               |             |                    |   be necessary
             |               |             |                    |   for hydrocephalus
             |               |             |                    | 4:Chemotherapy
             |               |             |                    |   may be used for
             |               |             |                    |   Grades 3 and 4.
_____________|_______________|_____________|____________________|____________________
 Hemispheric | Usually slow  | Hemispheres | Headache, nausea,  | 1:Surgery
  Astrocytoma| growing       | of brain    | vomiting,          | 2:Radiation
             |               |             | visual changes,    |   if not 
             |               |             | others depending   |   completely removed
             |               |             | on specific        | 3:Chemotherapy
             |               |             | location of tumor  |   may be used for
             |               |             |                    |   Grades 3 and 4
_____________|_______________|_____________|____________________|____________________
 Optic Nerve | Slow growing; | Along optic | Depends on         | 1:Surgery
  Glioma     | puts pressure | nerves,     | area along         | 2:Radiation
             | on surrounding| optic       | nerves. Maybe      |   if incomplete
             | important     | chiasm and  | dim vision,        |   removal or
             | areas         | hypothalamus| loss of half       |   removal not 
             |               |             | of vision,         |   possible
             |               |             | hormone imbalance  |
_____________|_______________|_____________|____________________|____________________
 Brain Stem  | May be slow   | Brain stem  | Double vision,     | 1:Surgery usually
  Glioma     | or fast       | (pons)      | facial weakness,   |   not possible
             | growing       |             | balance problems,  |   due to location
             |               |             | vomiting           | 2:Radiation
             |               |             |                    | 3:Chemotherapy
_____________|_______________|_____________|____________________|____________________
 Oligodendro-| Slow growing; | Hemispheres | Seizures,          | 1:Surgery
  glioma     | frequently    | of the      | headache,          | 2:Radiation
             | calcified.    | brain,      | vision problems    |   if not 
             | Arise from    | especially  |                    |   completely
             | cells which   | frontal and |                    |   removed
             | make the      | temporal    |                    | 3:Chemotherapy
             | myelin that   | lobes. More |                    |   may be used
             | insulates     | common in   |                    |
             | nerve fibres  | the thalamus|                    |
             |               | of children |                    |
_____________|_______________|_____________|____________________|____________________
 Ependymoma  | Usually slow  | Ventricles, | Signs of           | 1:Surgery:
             | growing; arise| especially  | hydrocephalus      |   removal if
             | from the cells| the fourth  | including          |   location allowed
             | that line the | ventricle   | headache, nausea,  | 2:Radiation:
             | ventricles    |             | vomiting, visual   |   may be used
             |               |             | disturbances       |   if child over
             |               |             |                    |   4 years (growth
             |               |             |                    |   and development
             |               |             |                    |   may be affected
             |               |             |                    |   under this age).
             |               |             |                    | 3:Chemotherapy may
             |               |             |                    |   be used
             |               |             |                    | 4:Shunting, if
             |               |             |                    |   necessary
_____________|_______________|_____________|____________________|____________________
 Ganglio-    | Usually       | Anywhere in | Seizures. There may| 1:Surgery is 
  gliomas    | slow growing  | brain; most | be intellectual and|   curative
             |               | common site | behavioral         | 2:Radiation if
             |               | is temporal | difficulties       |   entire tumor
             |               | lobe        |                    |   not removed 

Type of Tumor| Description| Location         | Signs & Symptoms | Treatment
_____________|____________|__________________|__________________|_________________
Medullo-     | Fast       | Cerebellum; may  | Short,           | 1:Surgery
 blastoma    | growing    | involve fourth   | progressive      | 2:Radiation of
             |            | ventricle, 3rd   | history of       |   brain and 
             |            | and neighbouring | headache,        |   spinal cord
             |            | ventricles, mid- | vomiting,        | 3:Chemotherapy 
             |            | brain, spinal    | loss of appetite |   may be used
             |            | cord; may involve| and there may be | 4:Shunting, 
             |            | seeding to other | coordination     |   if necessary
             |            | parts of brain,  | problems         |
             |            | spinal cord and  |                  |
             |            | other parts of   |                  |
             |            | body outside the |                  |
             |            | brain and spinal |                  |
             |            | cord             |                  |
_____________|____________|__________________|__________________|_________________
Cerebral     | Fast       | Throughout the   | Depends on       | 1:Surgery, total 
 neuro-      | growing    | brain and spinal | location         |   removal if
 blastomas,  |            | cord; tendency   |                  |   possible
Ependymo-    |            | seed             |                  | 2:Radiation
 blastomas,  |            |                  |                  | 3:Chemotherapy
Pineo-       |            |                  |                  |
 blastomas   |            |                  |                  |

Type of Tumor| Description| Location         | Signs & Symptoms | Treatment
_____________|____________|__________________|__________________|___________________
GERM CELL    |            | Pineal region    | Hydrocephalus,   | 1:Biopsy
 TUMORS:     |            |                  | visual           | 2:Surgery if
             |            |                  | difficulties     |   possible
Chorio-      | Fast       |                  | *Choriocarcinoma,| 3:Radiation
 carcinoma   | growing    |                  |  embryonal       | 4:Steroids
             |            |                  |  carcinoma and   | 5:Shunting may be 
Embryonal    | Fast       |                  |  endodermal sinus|   necessary
 carcinoma   | growing    |                  |  tumors can be   | 6:Chemotherapy   
             |            |                  |  diagnosed by a  |   may be used for
Endo-dermal  | Fast       |                  |  blood test or   |   germ cell tumors
 sinus tumor | growing    |                  |  cerebrospinal   |   and pineal 
             |            |                  |  fluid test      |   cell tumors
Germinomas   | Less fast  |                  |                  |
             | growing    |                  |                  |
             |            |                  |                  |
Dermoid cysts| Slow       | Pineal region and|                  |
             | growing    | skull            |                  |
             |            |                  |                  |
Epidermoid   | Slow       | Pineal region and|                  |
 cysts       | growing    | skull            |                  |
_____________|____________|__________________|                  |
PINEAL CELL  |            |                  |                  |
 TUMORS:     |            |                  |                  |
Pineo-       | Fast       | Pineal region    |                  |
 blastomas   | growing    |                  |                  |
             | (Actually a|                  |                  |
             | PNET of the|                  |                  |
             | pineal     |                  |                  |
             | gland)     |                  |                  |
             |            |                  |                  |
Pinealomas   | Slow       |                  |                  |
 (Pinealo-   | growing    |                  |                  |
  cytoma)    |            |                  |                  |
_____________|____________|__________________|                  |
GLIAL CELL   | Discussed  | Pineal region and|                  |
 TUMORS:     | under glial| other            |                  |
             | tumors     |                  |                  |

Type of Tumor| Description| Location         | Signs & Symptoms | Treatment
_____________|____________|__________________|__________________|___________________
Cysts        | Slow       | Pineal region    | Hydrocephalus,   | 1:Biopsy
             | growing    | and other        | visual           | 2:Surgery if
             |            |                  | difficulties     |   possible
             |            |                  | *Choriocarcinoma,| 3:Radiation
             |            |                  |  embryonal       | 4:Steroids
             |            |                  |  carcinoma and   | 5:Shunting may be 
             |            |                  |  endodermal sinus|   necessary
             |            |                  |  tumors can be   | 6:Chemotherapy may 
             |            |                  |  diagnosed by a  |   be used for germ 
             |            |                  |  blood test or   |   cell tumors and 
             |            |                  |  cerebrospinal   |   pineal cell tumors
             |            |                  |  fluid test      |
_____________|____________|__________________|__________________|_____________________
Meningiomas  | Slow       | Pineal region    | Discussed below  |
             | growing    | and other        | under meningiomas|
_____________|____________|__________________|__________________|_____________________
Cranio-      | Slow       | Along the        | Hydrocephalus;   | 1:Surgery, complete
pharyngiomas | growing,   | pituitary stalk; | hormonal         |   removal if possible
             | may be     | may involve the  | difficulties     | 2:Radiation if
             | cystic in  | hypothalamus,    | (e.g. growth     |   incomplete removal
             | nature     | optic nerve      | delay, diabetes);|
             |            | pathways and the | visual loss      |
             |            | third ventricle  | including        |
             |            |                  | decreased vision |
             |            |                  | and visual field |
             |            |                  | difficulties     |
_____________|____________|__________________|__________________|_____________________

Type of Tumor| Description| Location         | Signs & Symptoms | Treatment
_____________|____________|__________________|__________________|___________________
Papillomas   | Slow       | Lining of        | Hydrocephalus and| 1:Surgery
             | growing    | ventricular      | its associated   |
             |            | surface          | symptoms         |
_____________|____________|__________________|__________________|___________________
Carcinomas   | Fast       | Lining of        | Hydrocephalus and| 1:Surgery
             | growing    | ventricular      | its associated   | 2:Radiation
             |            | surface          | symptoms         | 3:Chemotherapy

Type of Tumor| Description| Location         | Signs & Symptoms | Treatment
_____________|____________|__________________|__________________|___________________
Space        | Slow       | Optic pathways;  | Symptoms related | 1:Surgery
occupying or | growing; do| pituitary gland  | to pressure on   | 2:Radiation if
non-secreting| not invade |                  | neighbouring     |   incomplete
tumors       | structures |                  | structures;      |   removal
             |            |                  | usually hormone  | 
             |            |                  | imbalance and    |
             |            |                  | visual problems  |
_____________|____________|__________________|__________________|___________________
SECRETING    | Tumors     | Pituitary gland  | Delay in expected| 1:Surgery
PITUITARY    | contain    |                  | onset of         | 2:Radiation
TUMORS:      | hormone    |                  | menstruation;    | 3:Drug therapy to 
 Prolactin   | secreting  |                  | lack of          |   reduce amount of 
 secreting   | cells and  |                  | menstruation;    |   hormone released
 adenomas    | may enlarge|                  | alterations in   |   by the tumor
             | glands     |                  | menstruation     | 4:Hormone 
             |            |                  | after it has     |   replacement
             |            |                  | started          |   may be required
             |            |                  | (amenorrhea)     |   after surgery
_____________|            |                  |__________________|
 Growth      |            |                  | Giantism,        |
 hormone     |            |                  | diabetes millitus|
 secreting   |            |                  |                  |
 adenomas    |            |                  |                  |
_____________|            |                  |__________________|
 ACTH        |            |                  | Overproduction of|
 (adreno-    |            |                  | cortisol can     |
  cortico-   |            |                  | impair response  |
  tropic)    |            |                  | to injury and    |
 secreting   |            |                  | infection;       |
 adenomas    |            |                  | decreased        |
             |            |                  | potassium        |

Type of Tumor| Description| Location         | Signs & Symptoms | Treatment
_____________|____________|__________________|__________________|___________________
Meningiomas  | Very slow  | Within the skull | Symptoms related | 1:Surgery
             | growing and| but on the       | to pressure on   | 2:Radiation, 
             | rare in    | outside of the   | neighboring      |   if incomplete
             | children   | brain            | structures       |   removal