Brain tumors—gliomas, medulloblastomas and ependymomas—are the second most common type of cancer in children. A new term has recently been designated for certain types of brain tumors—PNET, which stands for primitive neuroectodermal tumors.
Some cancers of children are rare in adults. A cancer of the sympathetic nervous system known as neuroblastoma may occur in the adrenal glands located on top of the kidneys or may originate anywhere there is a particular kind of nerve ending known as a sympathetic nerve ending—the chest, the abdomen, the pelvis and, rarely, other sites. A cancer of the kidney known as Wilms' tumor is also particular to children, occurring most commonly in children two to four years of age and rarely in those over 16. It may occur in one or both kidneys.
Other childhood tumors that are uncommon in adults are a tumor of the membrane at the back of the eye, the retina, called retinoblastoma; a muscle tumor called rhabdomyosarcoma; teratomas, which are tumors of young cells known as germ cells; and a tumor of the liver known as hepatoblastoma.
Bone tumors such as osteogenic sarcoma , Ewing's sarcoma or chondrosarcoma occur in children, particularly teenagers. Histiocytosis X or Langerhans cell histiocytosis is not a malignancy but is often cared for by physicians who specialize in pediatric cancer therapy.
Children, like adults, develop lymphomas known as Hodgkin's disease and non-Hodgkin's lymphoma. They may also have tumors of the liver (hepatomas), skin cancer (melanoma, which is rare) and cancers of the thyroid, adrenal glands and blood vessels.
