MedGen

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]

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]

The most frequent histological variant of diffuse astrocytoma. It is predominantly composed of fibrillary neoplastic astrocytes. Nuclear atypia is a diagnostic criterion but mitotic activity, necrosis and microvascular proliferation are absent. The occasional or regional occurrence of gemistocytic neoplastic cells is compatible with the diagnosis of fibrillary astrocytoma. (WHO) [from NCI]

A rare variant of diffuse astrocytoma. It is characterized by the presence of a conspicuous, though variable, fraction of gemistocytic neoplastic astrocytes. Gemistocytes are round to oval astrocytes with abundant, glassy, non-fibrillary cytoplasm which appears to displace the dark, angulated nucleus to the periphery of the cell. To make the diagnosis of gemistocytic astrocytoma, gemistocytes should amount to more than approximately 20% of all tumor cells. (Adapted from WHO) [from NCI]

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]

A rare, high-grade, malignant glial tumor, histologically characterized by abundance of pleomorphic astrocytes and multiple mitotic figures, often associated with diffuse infiltration of the surrounding tissue, considerable edema and mass effect and involvement of the contralateral brain. Depending on the primary localization of the tumor, patients can present with signs of raised intracranial pressure (headache, vomiting, papilledema), seizures, progressive neurological deficits, and/or behavioral changes. The tumor is most commonly localized in the frontal and temporal lobes, brain stem and spinal cord. [from ORDO]

The most common form of astrocytoma (WHO Grade I) in childhood. These typically have MAPK signaling pathway abnormalities. [from HPO]

An astrocytoma that arises from the cerebral hemispheres. [from NCI]

A demarcated, largely intraventricular tumor in the region of the foramen of Monro composed of spindle to large plump or ganglion-like cells with eosinophilic to amphophilic cytoplasm and somewhat pleomorphic nuclei with occasional prominent nucleoli. These tumors are almost always associated with tuberous sclerosis. [from HPO]

A rare low-grade astrocytoma characterized by a high degree of cellular differentiation, slow growth, and diffuse infiltration of adjacent brain structures, and corresponding to WHO grade II. The tumor typically affects young adults and has an intrinsic tendency for progression to high-grade glioma. Histological variants are fibrillary, gemistocytic, and protoplasmic astrocytoma. Patients most commonly present with seizures, but also with other neurological or neuropsychological abnormalities, depending on the location. [from ORDO]

A pilocytic astrocytoma that occurs during adolescence. [from NCI]