Autoantibodies/immunology; Autoantigens/immunology; Autoimmune Diseases of the Nervous System/etiology; ELAV Proteins/immunology; Ganglioneuroma/complications; Neoplasms, Multiple Primary/complications; Neuroblastoma/complications; Para-Aortic Bodies/pathology; Paraneoplastic Syndromes, Nervous System/etiology; Retroperitoneal Neoplasms/complications; Survivors; Antibodies, Viral/blood; Antineoplastic Combined Chemotherapy Protocols/therapeutic use; Autoantibodies/blood; Autoimmune Diseases of the Nervous System/diagnostic imaging; Autoimmune Diseases of the Nervous System/immunology; Combined Modality Therapy; Diagnostic Errors; Female; Ganglioneuroma/diagnosis; Ganglioneuroma/surgery; Humans; Hyperthermia, Induced; Lymphocytes, Tumor-Infiltrating/immunology; Measles-Mumps-Rubella Vaccine/immunology; Multiple Sclerosis/diagnosis; Neoplasm Recurrence, Local/drug therapy; Neoplasm Recurrence, Local/radiotherapy; Neoplasm Recurrence, Local/surgery; Neoplasms, Multiple Primary/diagnosis; Neoplasms, Multiple Primary/surgery; Neuroblastoma/diagnosis; Neuroblastoma/immunology; Neuroblastoma/therapy; Optic Atrophy/diagnosis; Optic Atrophy/etiology; Paraneoplastic Syndromes, Nervous System/diagnostic imaging; Paraneoplastic Syndromes, Nervous System/immunology; Peripheral Blood Stem Cell Transplantation; Radionuclide Imaging; Radiotherapy, Adjuvant; Retroperitoneal Neoplasms/diagnosis; Retroperitoneal Neoplasms/immunology; Retroperitoneal Neoplasms/therapy; T-Lymphocyte Subsets/immunology; Young Adult