Inclusion Criteria:

- Diagnosis:

- Relapsed/refractory neuroblastoma with original diagnosis based on tumor
histopathology or elevated urine catecholamines with typical neuroblastoma cells
in the bone marrow

- Metastatic pheochromocytoma

- Age >1 year and able to cooperate with radiation safety restrictions during therapy
period

- Karnofsky or Lansky performance status of ≥ 50%

- Life expectancy: patients must have a life expectancy of at least 8 weeks

- Disease status: Failure to respond to standard therapy (usually combination
chemotherapy with or without radiation and surgery) or development of progressive
disease at any time (any new lesion or an increase in size >25% of a pre-existing
lesion). Patients may enter this study with or without re-induction therapy for
recurrent tumor.

- Disease must be evaluable by MIBG scan. A positive MIBG scan must be present within 8
weeks prior to study entry and subsequent to any intervening therapy. If the patient
has only one MIBG positive lesion and that lesion was radiated, a biopsy must be done
at least 4 weeks after radiation was completed and must show viable neuroblastoma.

- Stem Cells: If a patient does not have a hematopoietic stem cell product available
for re-infusion after MIBG treatment, they may not receive a 131I-MIBG dose >12
mCi/kg. Patients must have a hematopoietic stem cell product available for reinfusion
after MIBG treatment at doses of > 12 mCi/kg. The minimum quantity for peripheral
blood stem cells is 1.0 x 106 CD34+ cells/kg (optimum > 2 x 106 CD34+ cells/kg). The
minimum dose for bone marrow is 1.0 x 108 mononuclear cells/kg (optimum >2.0 x 108
mononuclear cells/kg).

- Stem cell source: The majority of patients on this protocol will have autologous
PBSCs available. Where a syngeneic donor is available, this donor may also be
utilized. In the case of a patient who has received a prior allogeneic transplant, if
the donor is available, allogeneic stem cells may be utilized. For these patients, 3
criteria must be met: 1) there must be no evidence of graft vs. host disease (GVHD),
2) the patient must be on no medication for GVHD treatment or prophylaxis and 3)
there must be full donor chimerism (>95% donor on peripheral blood chimerism
testing). The only acceptable allogeneic product is CD34- selected PBSC (which will
minimize the risk of GVHD).

- Have acceptable organ function as defined below within 7 days of enrollment:

- Bone Marrow: ANC ≥750 X 109 /L and platelets ≥50,000 X 109 /L without
transfusion if stem cells are not available (any ANC or platelet allowed if stem
cells available)

- Renal: Creatinine ≤3x upper limit of normal

- Hepatic: Bilirubin ≤2x upper limit of normal; AST/ALT ≤10x upper limit of normal

- Cardiac: Ejection fraction ≥45% on echocardiogram

- Pulmonary: normal lung function as manifested by no dyspnea and/or oxygen
saturation ≥ 88% on room air.

- Prior Therapy: Patients must have recovered from all acute toxicities (defined as
CTCAE 4.0 ≤ grade 1) associated with any prior therapy, and:

- Myelosuppressive chemotherapy: At least 2 weeks should have elapsed since any
chemotherapy causing myelosuppression

- Biologic (anti-neoplastic agent): At least 7 days should have elapsed since the
completion of therapy with a biologic agent.

- Monoclonal antibodies: At least 3 half-lives should have elapsed since therapy
with a monoclonal antibody

- Radiation therapy: Three-months should have elapsed in the case of completing
radiation to any of the following fields: craniospinal, total abdominal, whole
lung, total body irradiation). For all other sites of radiation, at least 2
weeks should have relapsed.

- Cytokine therapy (e.g. G-CSF, GM-CSF, IL-6, IL-2): must be discontinued a
minimum of 24 hours prior to MIBG therapy.

- Voluntary written informed consent must be obtained before performance of any
study-related procedure not part of normal medical care, with the understanding that
consent may be withdrawn by the subject at any time without prejudice to future
medical care.

Exclusion Criteria:

- Patients with disease of any major organ system that would compromise their ability
to withstand therapy.

- Because of the teratogenic potential of the study medication, no patients who are
pregnant or lactating will be allowed. Patients of childbearing potential must
practice an effective method of birth control while participating on this study, to
avoid possible damage to the fetus.

- Known allergy to any of the agents or their ingredients used in this study.

- Patients who are on hemodialysis

- Patients with untreated positive blood cultures or progressive infections as assessed
by radiographic studies