Iodine I 131 Monoclonal Antibody 3F8 in Treating Patients With Central Nervous System Cancer or Leptomeningeal Cancer

Inclusion Criteria: * Patients must have a histologically confirmed diagnosis of a malignancy known to expressGD2. Such tumors include medulloblastoma/primitive neuroectodermal tumor of the CNS, high grade astrocytomas, malignant glioma, neuroblastoma, retinoblastoma, ependymoma, rhabdoid tumors, sarcomas, melanoma or small cell lung carcinoma. For patients with other tumor types, GD2 expression must be confirmed by immunohistochemical staining and assessed by the Department of Pathology using prior frozen tissue, bone marrow or CSF cytology (send to Research Lab). * Patients must have CNS/ leptomeningeal disease including high risk medulloblastoma, or a CNS/leptomeningeal malignancy which is refractory to conventional therapies, or for which no conventional therapy exists, OR a recurrent brain tumors with a predilection for leptomeningeal dissemination (medulloblastoma, PNET, rhabdoid tumor). * Patients must have an absolute neutrophil count (ANC) \> 1000/ul and a platelet count \> 50,000/ul. * Patients may have active malignancy outside the central nervous system. * Patients who have a programmable shunt will not be excluded. * Both pediatric and adult patients of any age are eligible. * Patients or a legal guardian will sign an informed consent form approved by the IRB and obtained by the Principal or a Co- Investigator before patient entry. Minors will provide assent. Exclusion Criteria: * Patients with obstructive or symptomatic communicating hydrocephalus. * Patients…