Pineal and Germ Cell Tumors

Pineal region tumors account for about 1 percent of all brain tumors. They can be extremely difficult to diagnose and treat because of their location. Tissue confirmation is important because of the varied histologies found in this region as well as the implications of these differences in influencing treatment options. Occasionally, small samples of benign lesions may be confused with more malignant processes.

Patients with pineal region tumors often present with symptoms of hydrocephalus caused by compression of the cerebral aqueduct that result in elevated intracranial pressure (..I§.ble46z8 ). Patients may present acutely with nausea, vomiting, lethargy, headaches, or changes in sensorium and mentation. Enlargement and infiltration of the nearby structures, including the midbrain, may lead to a kinetic mutism. Further expansion to involve the superior colliculus can lead to Parinaud's syndrome, characterized by paralysis of upgaze, near-light dissociation, and convergence-retraction nystagmus. Further compression may result in paralysis of downgaze. In patients with germ cell tumors, precocious puberty, especially in boys, may be observed.

The primary differentiation of lesions in this location can be separated into tumors and cysts or, in infants, a vein of Galen aneurysm. Tumors can be divided into germ cell tumors (germinomas, teratomas, or choriocarcinomas), intrinsic pineal tumors (pinealcytomas or pinealblastomas),

TABLE 46-8 -- PRESENTATION AND EVA

LUATION OE PINEAL REGION LESIONS

Type

Clinical Presentation

Evaluation

Treatment

Germ cell tumor

Headache, Parinaud's syndrome, endocrine dysfunction, nausea, vomiting, diabetes insipidus

MRI with gadolinium, hormone evaluation; when feasible, CSF evaluation including beta-hCG

Biopsy radiotherapy

Pineoblastoma

Headache, Parinaud's syndrome, endocrine dysfunction, nausea, vomiting

MRI with gadolinium

Resection radiotherapy

Glial neoplasms (astrocytomas, ependymomas, etc)

Slowly progressive, headache, nausea, vomiting

MRI with gadolinium

Resection, chemotherapy, radiotherapy

Meningioma

Slowly progressive, headache, late nausea, vomiting

MRI with gadolinium

Resection, radiotherapy with incomplete resection

Lymphoma

Headache, Parinaud's syndrome, endocrine dysfunction, nausea, vomiting, diabetes insipidus

MRI of craniospinal contents; when feasible, CSF evaluation including beta-2 microglobulin

Biopsy, chemotherapy, (?) radiotherapy

Metastatic tumors

Often history of cancer

MRI with gadolinium, evaluation for other metastatic deposits

Resection, radiotherapy, (?) chemotherapy

Pineal cysts

Slowly progressive, headache, late nausea, vomiting, or incidental finding

MRI with gadolinium

Observation, reduction

Vein of Galen

Most commonly male, high cardiac output, cranial bruit, enlarging head

CT with contrast

Surgery, (?) embolization

CSF, Cerebrospinal fluid; CT, computed tomography; hCG, human chorionic gonadotropin; MRI, magnetic resonance imaging.

metastatic lesions, or other tumors including ependymomas, astrocytomas, or meningiomas. Patients should undergo MRI with gadolinium or, if this is unavailable, CT with a suitable contrast agent. This will help to localize the tumor and define the involvement of local structures. Occasionally, angiography is required for surgical planning or to exclude an aneurysm of the vein of Galen.

MRI can help in differentiating possible pathological causes. For example, teratomas usually contain fat and calcium, whereas meningiomas may reveal a dural tag. All patients should undergo cerebrospinal fluid analysis including cytological examination when feasible. Measurement of alpha-fetoprotein and beta-human chorionic gonadotropin (hCG) in the CSF should be compared with serum levels. Any clinical evidence of pituitary dysfunction should prompt thorough endocrinological studies.

Pineal region tumors require histological confirmation. Total resection is curative for benign lesions, whereas maximum resection may improve the overall survival of patients with malignant lesions. Hydrocephalus requiring shunting is common. Pineal or germ cell tumors require postoperative MRI for evaluation of seeding of the cerebrospinal pathway. Patients with germ cell tumors should undergo CSF evaluation when feasible. Testing should include a comparison of serum with cSf beta-hCG and alpha-fetoprotein, which can be used as markers for disease. Radiotherapy can be curative for localized lesions. Patients with evidence of cerebrospinal dissemination require craniospinal radiation. Because these tumors are so radiation sensitive, the use of chemotherapy with cisplatin and etoposide has often been reserved for patients with recurrent disease or those with more malignant tumors such as yoke-sac tumors or malignant choriocarcinoma. Although systemic germ cell tumors are very sensitive to chemotherapy, CNS germ cell tumors appear to be less responsive. Use of chemotherapy before or after primary treatment with radiotherapy remains to be studied. Relapse most commonly occurs locally or with CSF dissemination. Overall, survival approaches 75 percent at 5 years, and survival of patients with germinomatous germ cell tumors is over 90 percent.

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