Diagnosis: Pilocytic Astrocytoma

Findings: Neoplasm Name: Pilocytic Astrocytoma Synonyms: Juvenile pilocytic, spongioblastoma ICD-O code: Cell of Origin: Astrocyte WHO Grade(s): Grade 1 Genetics and Associations: Occures in the optic nerve in NF-1 Demographics (Age, Sex, Incidence): Most common in childhood, with a peak incidence 9 - 15 years. Slight female predilection (13:9 F>M). Accounts for approximately 1/3 of pediatric posterior fossa neoplastic masses. Common Locations: Cerebellum >> hypothalamus > brainstem, cerebral hemisphere, spinal cord Gross Appearance: Circumscribed with very narrow zone of infiltration, mural nodule and fluid collection ("cyst") Histology: biphasic with dense and loose areas, microcysts, Rosenthal fibers Special Stains: Radiology: "cyst with nodule" showing intense enhancement of nodule on MR and CT. Largely hypovascular or avascular on angiography Progression: Does not progress Prognosis and Treatment: Surgical resection is often curative COMMENTS: Most benign of astrocytoma types, most common subtype of astrocytoma in posterior fossa in children, most common type of hypothalamic glioma

Ddx: Neoplasm Name: Pilocytic Astrocytoma Synonyms: Juvenile pilocytic, spongioblastoma ICD-O code: Cell of Origin: Astrocyte WHO Grade(s): Grade 1 Genetics and Associations: Occures in the optic nerve in NF-1 Demographics (Age, Sex, Incidence): Most common in childhood, with a peak incidence 9 - 15 years. Slight female predilection (13:9 F>M). Accounts for approximately 1/3 of pediatric posterior fossa neoplastic masses. Common Locations: Cerebellum >> hypothalamus > brainstem, cerebral hemisphere, spinal cord Gross Appearance: Circumscribed with very narrow zone of infiltration, mural nodule and fluid collection ("cyst") Histology: biphasic with dense and loose areas, microcysts, Rosenthal fibers Special Stains: Radiology: "cyst with nodule" showing intense enhancement of nodule on MR and CT. Largely hypovascular or avascular on angiography Progression: Does not progress Prognosis and Treatment: Surgical resection is often curative COMMENTS: Most benign of astrocytoma types, most common subtype of astrocytoma in posterior fossa in children, most common type of hypothalamic glioma