PEDBASE.org - The Pediatric Database - Detailed information of CEREBELLAR ASTROCYTOMA

CEREBELLAR ASTROCYTOMA

DEFINITION:

A neuroglial solid tumor of the cerebellum characterized by obstructive hydrocephalus and cerebellar signs.

EPIDEMIOLOGY:

incidence: ?
- 2nd most common tumor of the posterior fossa
- accounts for 10-20% of all pediatric brain tumors
age of onset:
- constant throughout childhood
- infants rarely affected
risk factors:
- M = F
- neurofibromatosis

PATHOGENESIS:

1. Tumor Origin

obstructive hydrocephalus results from the local extension of the tumor mass into the cerebellar peduncles, brainstem, and leptomeninges
tends to be midline (solid) in children and lateral (cystic) in adolescence

2. Histologic Types

two types:

1. Juvenile Pilocystic Astrocytoma (JPA)

85% of cases; 5 yr. survival: 94%
alternating areas of high and low cellularity
microcysts coalesce -> classic cystic cerebellar JPA
usually low grade

2. Diffuse Astrocytoma

15% of cases; 5 yr. survival: 38%
usually solid and infiltrative
transformation to anaplastic astrocytoma in 10% of cases
more common in young adults and in neurofibromatosis

average duration of symptoms prior to diagnosis is 15 months reflecting the indolent nature of the tumor
may be associated with abnormalities in chrom. 17

3. Pathology

protoplasmic and fibrillary astrocytes interspered with
Rosenthal fibres

4. Poor Prognosticators

large volume of residual tumor
midline solid tumor (more extensive)
diffuse astrocytoma variant

CLINICAL FEATURES:

1. Primary Tumor

obstructive hydrocephalus with increased intracranial pressure
- diplopia, headache, nausea and vomiting, papilledema
cerebellar signs
- vermis, lateral, anterior, visual

2. Metastases

1. Leptomeningeal - distant metastases are rare and associated with anaplastic astrocytomas

INVESTIGATIONS:

1. Imaging Studies

1. MRI

with gadolinium can help differentiate solid (midline) tumors from cystic with mural nodule (lateral) tumors

2. Pathology

tumor

3. Biologic

CSF - cytology

MANAGEMENT:

1. Surgery

curative - total resection - 100% survival at 10 years
- 95% survival at 25 years
partial resection - 85% survival at 5 years; (JPA)
- 38% survival at 5 years; (diffuse)
through a suboccipital craniectomy
mobidity - cerebellar symptoms, pseudobulbar palsy, infections

2. Cranial Irradiation

adjuvant
indications
- residual tumor of diffuse astrocytoma variant
- brainstem involvement
- high grade astrocytoma
long term follow-up is necessary since 40% of recurrences occur five years after diagnosis

Pediatric Database - CEREBELLAR ASTROCYTOMA

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