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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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