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108 P. Imbach

9.12.6.2 Pathology

Germ cell tumors (germinoma, embryonal carcinoma, choriocarcinoma, teratoma)

Pinealoblastoma (primitive neuroectodermal tumor, PNET)

Astrocytoma I–IV with cystic parts, mainly well differentiated; occasionally infiltrating in adjacent tissue

9.12.6.3 Clinical Manifestation

Parinaud syndrome characteristic; also see 9.6.3.3, page 95

9.12.6.4 Laboratory Diagnosis

Serum and cerebral fluid level of á-fetoprotein (AFP) and/or ®-choriogonadotropin (®-HCG) in mixed germ cell tumors often high (also called nongerminoma germ cell tumors – NGGCT)

In choriocarcinoma, high level of ®-HCG alone

Cerebral fluid analysis with positive results for AFP and ®-HCG, which exclude the necessity of biopsy

9.12.6.5 Radiological Diagnosis

MRI or CT in teratoma or pinealoblastoma: hyperdense tumor with marked contrast enhancement, often with calcifications, especially in children below the age of 6 years

9.12.6.6 Therapy

Special surgical techniques (microscopic, stereotactic procedure) facilitate biopsy and partial resection

Radiotherapy: indicated especially in germinoma (highly radiosensitive) with involved-field irradiation in combination with chemotherapy with reduced irradiation dosage (35–50 Gy); pinealoblastoma: procedure as in medulloblastoma (see above)

Chemotherapy: similar in germ cell tumors treatment as in peripheral germ cell tumors

9.12.6.7 Prognosis

Variable, depending on tumor type

Germ cell tumors: more than 90% event-free survival

Germinoma, choriocarcinoma, and yolk sac tumors: prognosis depending on tumor extension, but, in general, 5-year survival rates of 70–80% with chemotherapy and craniospinal radiation

Pinealoblastoma as for medulloblastoma

9.12.7 Ependymoma

9.12.7.1 Incidence

Nine percent of brain tumors

Ratio of males to females is 1.6:1

Peak incidence between 2–6 years of age

9 Brain Tumors

109

 

 

Supraand infratentorial appearance:

Mainly in the area of the fourth ventricle with hydrocephaly

One-third in the area of the lateral ventricle

Eight to ten percent involve the spinal cord and, in particular, the cauda equina

9.12.7.2 Pathology and Genetics

Often solid tumors, occasionally with calcification; invasive growth into the adjacent tissue

Metastases to spinal column (drop metastases), 7–12% incidence

Microscopically three forms observed

Highly cellular ependymoma with tubular structures, rosettes, and pseudorosette formation: WHO Grade II

Highly malignant variant: disorganized histology, pleomorphic, high rate of mitosis and necrosis, and highly vascular, e.g., anaplastic ependymoma: WHO Grade III

Myxopapillary ependymoma: rare; well-differentiated cells, which contain mucus: WHO Grade I

Special form: choroid plexus papilloma arising in the lateral ventricle, causing overproduction of cerebral fluid and development of hydrocephaly

Genetic alterations in predisposition syndromes: NF 2, Turcot syndrome

Ependymomas from different regions of the CNS are molecularly distinct disorders

Expansion profiles of neural progenitor cells as radial glia (like cancer stem cells)

9.12.7.3 Clinical Manifestations and Diagnosis

Similar to medulloblastoma (especially in the area of the fourth ventricle): headache, vomiting, ataxia

9.12.7.4 Therapy

Surgical procedure:

Rarely radical tumor resection is possible

For residual tumor of more than 1.5 cm3 after chemotherapy, more surgery with intraoperative microscopy necessary

Surgical morbidity and lethality high

Radiotherapy:

Supratentorial ependymoma without dissemination: cranial irradiation

All other stages and locations as for medulloblastoma

Chemotherapy:

As for medulloblastoma (see above)

9.12.7.5 Prognosis

Depends on degree of surgical resection as for medulloblastoma

Residual tumor more than 1.5 cm3 results in long-term survival of less than 20%

After radical resection, chemotherapy is used in patients without cerebral fluid dissemination: 65.75% long-term survival. i

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