MedGen

An inherited malignant tumor that originates in the nuclear layer of the retina. A predisposition to retinoblastoma has been associated with 13q14 cytogenetic abnormalities affecting the RB1 gene. Patients with the inherited form appear to be at increased risk for secondary non-ocular malignancies such as osteosarcoma, malignant fibrous histiocytoma, and fibrosarcoma. [from NCI]

Retinoblastoma is a malignant tumor of the developing retina that occurs in children, usually before age five years. Retinoblastoma develops from cells that have cancer-predisposing variants in both copies of RB1. Retinoblastoma may be unifocal or multifocal. About 60% of affected individuals have unilateral retinoblastoma with a mean age of diagnosis of 24 months; about 40% have bilateral retinoblastoma with a mean age of diagnosis of 15 months. Heritable retinoblastoma is an autosomal dominant susceptibility for retinoblastoma. Individuals with heritable retinoblastoma are also at increased risk of developing non-ocular tumors. [from GeneReviews]

Oligoastrocytoma is a type of low-grade glioma with a mixed astrocytoma and oligodendroglioma histology, manifesting with headaches, speech and motor problems, seizures and, in some, subarachnoid haemorrhage. [from ORDO]

A rare variant of diffuse astrocytoma. It is predominantly composed of neoplastic astrocytes showing a small cell body with few, flaccid processes with a low content of glial filaments and scant GFAP expression. This lesion is not well defined and is considered by some authors as an occasional histopathological feature rather than a reproducibly identifiable variant. When occurring in children, this neoplasm may be difficult to separate from pilocytic juvenile astrocytoma. (Adapted from WHO) [from NCI]

Glioblastomas are malignant astrocytic tumors (grade IV according to the WHO classification). [from ORDO]

Astrocytoma is a neoplasm of the central nervous system derived from astrocytes. Astrocytes are a type of glial cell, and thus astrocytoma is a subtype of glioma. [from HPO]