11 Of the larger studies that were more strictly confined to the congenital time period, i.e. all cases less than or equal to two months of age, teratomas and astrocytomas were usually the most frequent tumour type. (touchoncology.com)
Teratomas (from Greek teras, meaning "monster," and - oma, a suffix denoting a tumor or neoplasm) and other germ cell tumors are relatively common solid neoplasms in children. (medscape.com)
Teratomas may be classified as mature or immature on the basis of the presence of immature neuroectodermal elements within the tumor. (medscape.com)
Glial1
Although the polar spongioblastoma has historically been considered to be of primitive glial origin, the evidence of the polar spongioblastoma's very existence is questionable and is thought to be more akin to a growth pattern than a specific histologic type that may occur in either gliomas or tumors of neuronal origin. (medscape.com)
Astrocytomas4
Astrocytomas are represented by a wide variety of histologic forms and grades of tumors with a common histologic lineage. (medscape.com)
Tumors classified as astrocytomas can be further subdivided into the diffusely infiltrative astrocytomas, as well as the expansile, or circumscribed, astrocytomas. (medscape.com)
Pilocytic astrocytomas are slow growing tumors with an expansile growth pattern and little propensity to disseminate resulting, overall, in an excellent prognosis, as represented in the WHO grade (grade I). These tumors primarily arise in children and young adults but may remain asymptomatic until later in life. (medscape.com)
Of clinical importance is the occurrence of these tumors in the brainstem, where they may be mistaken for a diffusely infiltrating fibrillary astrocytomas. (medscape.com)
Arise1
These tumors are grouped together because they all appear to arise from postmeiotic germ cells. (medscape.com)
Grade2
[ 5 , 6 ] Similarly, the pilomyxoid astrocytoma, which is most commonly found in or around the optic chiasm and hypothalamus, has a propensity to early recurrence and infiltration, a fact that resulted in the WHO Committee upgrading this particular variant to a grade II tumor. (medscape.com)
Mature tumors (grade 0) have no immature elements. (medscape.com)
Types2
2,3,5-13 Ascertaining the frequency of individual congenital tumour types is often made difficult by the inclusion of older children in some analyses (up to 18 months of age in one study). (touchoncology.com)
Locations and specific tumor types depend on the age of the child. (medscape.com)
Origin4
Tumors of a controversial nature and, therefore, not discussed in this article include the astroblastoma that is now best considered to be of uncertain histologic origin with ultrastructural features of tanycytes. (medscape.com)
Several theories about the origin of these tumors are recognized. (medscape.com)
In 1965, Teilum first suggested the germ cell origin of gonadal tumors. (medscape.com)
and the tumor suppressor genes WT1 and MASH2 are imprinted, depending on their maternal or paternal origin. (medscape.com)
Common2
Pilocytic astrocytoma is the most common intracranial tumor in patients with neurofibromatosis type I , and these lesions are largely confined to the optic nerve. (medscape.com)
They constitute 23.5% of pediatric central nervous system (CNS) tumors and are the most common variant of glioma in children. (medscape.com)
Elements1
These malignant elements are typically yolk sac tumors but may also represent primitive neuroectodermal tumor (PNET). (medscape.com)