Inclusion Criteria:

- Patients must have the diagnosis of (a) DSRCT with peritoneal involvement or (b)
other 8H9-positive solid tumors involving the peritoneum (e.g. adrenocortical
carcinoma, Wilm's tumor).

- For tumors other than DSRCT, patients must have a history of tumor progression or
recurrence or failure to achieve complete response with standard therapy or <20%
chance of long term disease-free survival.

- For tumors other than DSRCT, 8H9 reactivity must be confirmed by
immunohistochemistry.

- Patients with DSCRT are not required to have measurable or evaluable disease.

- Patients with tumors other than DSRCT without measurable or evaluable disease will
only be considered if they have <20% chance of long term disease-free survival.

- Prior Therapy: At least 4 weeks should have elapsed since any biologic therapy, or
immunotherapy. Three weeks should have elapsed since last dose of chemotherapy or
radiotherapy.

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

- Stem cells: Patients must have an autologous hematopoietic stem cell product
cryopreserved and available for re-infusion after 131 I-8H9 treatment. The minimum
dose for hematopoietic stem cells is 2 x 106 CD34+ cells/kg.

- Minimum life expectancy of six weeks as determined by consenting professional.

- Signed informed consent indicating awareness of the investigational nature of this
program.

Exclusion Criteria:

- Severe major organ toxicity. Renal, cardiac, hepatic, pulmonary, gastrointestinal and
neurologic toxicity should all be grade 1 or less (per NCI CTC version 3 criteria)
with the following exceptions: serum AST,ALT and alkaline phosphatase should be ≤5 x
upper limit of normal (ULN), serum bilirubin ≤ 3 x ULN and nausea and vomiting should
be ≤ grade 2 Patients with myelosuppression are not excluded if ANC ≥ 500/uL.

- Platelet count should be > 50,000/ul and hemoglobin should be > 8gm/dl. Patients may
receive platelet or red blood cell transfusions to maintain hemoglobin and platelets
at clinical appropriate levels.

- Patients with clinically suspected dense intraperitoneal adhesions preventing
adequate IP distribution.

- History of allergy to mouse proteins.

- Patients previously treated with murine monoclonal antibodies will be excluded if
they have a HAMA level of >1000U/ml.

- Active serious infections not controlled by antibiotics.

- Pregnant women and women who are breast feeding are excluded for fear of danger to
the fetus/infant. Therefore negative pregnancy test is required for all women of
child-bearing age, and appropriate contraception is used during the study period.
Pregnancy testing will be carried out within two weeks prior to administration of
radioiodinated 8H9 in females of childbearing age.

- Inability or unwillingness to comply with radiation safety procedures or protocol
requirements.