Pilocytic astrocytoma is a relatively circumscribed, slowly growing, and is often cystic lesion.
It commonly occurs in in children and young adults.
It is histologically characterized by a biphasic pattern with varying proportions of compacted bipolar cells associated with Rosenthal fibers and loose -textured multipolar cells associated with microcysts and eosinophilic granular bodies.
Rosenthal fibers are intracytoplasmic corkscrew-shaped, brightly eosinophilic, hyaline masses.
Pilocytic astrocytoma corresponds to WHO grade1. Pilocytic astrocytomas comprise approximately 5% of all gliomas. It is the most common glioma in children, in whom the majority ( 67%) arise in the cerebellum.
Preferred sites include the optic nerve, optic chiasma/ hypothalamus, thalamus and basal ganglia, cerebral hemispheres , cerebellum and brain stem.
Involvement of the subarachnoid space is a common finding in pilocytic astrocytoma. It is not indicative of aggressive or malignant behavior, nor does it pretend subarachnoid dissemination.
Pilocytic astrocytoma may also seed the neuraxis.
Pilocytic astrocytomas are remarkable in maintaining their WHO grade I status over years and even decades. Very rarely, especially when previously irradiated, a malignat transformation may occur.
As with other CNS lesions, the neurological sign and symptoms depend on the location and size of the tumor. similarly non localizing signs like macrocephaly, headache, endocrinopathy are also seen. Seizures are uncommon since the lesions infrequently involve the cerebral cortex. Visual loss, hypothalamic and pituitary dysfunction like obesity and diabetes insipidus may occur.
CT scan brain with contrast or MRI brain with contrast with MR spectroscopy helps in preoperative provisional diagnosis of the lesion. The cysts may be either solitary and massive , the tumor being a mural nodule, or multiple, smaller and intratumoral.
Pilomyxoid Astrocytoma
A piloid neoplasm, closely related to pilocytic astrocytoma, that has a prominant mucoid matrix and angiocentric arrangement of monomorphous, bipolar tumor cells, without Rosenthal fibers or eosinophilic granular bodies/ hyaline deposits. Pilomyxoid astrocytoma corresponds to
WHO Grade II neoplasm. It typically presents in very young age group , median 10 months.
It commonly occurs in in children and young adults.
It is histologically characterized by a biphasic pattern with varying proportions of compacted bipolar cells associated with Rosenthal fibers and loose -textured multipolar cells associated with microcysts and eosinophilic granular bodies.
Rosenthal fibers are intracytoplasmic corkscrew-shaped, brightly eosinophilic, hyaline masses.
Pilocytic astrocytoma corresponds to WHO grade1. Pilocytic astrocytomas comprise approximately 5% of all gliomas. It is the most common glioma in children, in whom the majority ( 67%) arise in the cerebellum.
Preferred sites include the optic nerve, optic chiasma/ hypothalamus, thalamus and basal ganglia, cerebral hemispheres , cerebellum and brain stem.
Involvement of the subarachnoid space is a common finding in pilocytic astrocytoma. It is not indicative of aggressive or malignant behavior, nor does it pretend subarachnoid dissemination.
Pilocytic astrocytoma may also seed the neuraxis.
Pilocytic astrocytomas are remarkable in maintaining their WHO grade I status over years and even decades. Very rarely, especially when previously irradiated, a malignat transformation may occur.
As with other CNS lesions, the neurological sign and symptoms depend on the location and size of the tumor. similarly non localizing signs like macrocephaly, headache, endocrinopathy are also seen. Seizures are uncommon since the lesions infrequently involve the cerebral cortex. Visual loss, hypothalamic and pituitary dysfunction like obesity and diabetes insipidus may occur.
CT scan brain with contrast or MRI brain with contrast with MR spectroscopy helps in preoperative provisional diagnosis of the lesion. The cysts may be either solitary and massive , the tumor being a mural nodule, or multiple, smaller and intratumoral.
Pilomyxoid Astrocytoma
A piloid neoplasm, closely related to pilocytic astrocytoma, that has a prominant mucoid matrix and angiocentric arrangement of monomorphous, bipolar tumor cells, without Rosenthal fibers or eosinophilic granular bodies/ hyaline deposits. Pilomyxoid astrocytoma corresponds to
WHO Grade II neoplasm. It typically presents in very young age group , median 10 months.
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