AHEP0731, Treatment of Children with All Stages of Hepatoblastoma with Temsirolimus (IND#122782, NSC#683864) Added to High Risk Stratum Treatment

* Patients must be <= 21 years of age at the time of diagnosis. * Patients must be newly diagnosed with histologically-proven hepatoblastoma. In emergency situations when a patient meets all other eligibility criteria and has had baseline required observations as outlined in the protocol, but is too ill to undergo a biopsy safely, the patient may be enrolled on AHEP0731 without a biopsy. For a patient to maintain eligibility for AHEP0731 when emergent treatment is given, the following must occur: The patient must have a clinical diagnosis of hepatoblastoma, including an elevated alpha-fetoprotein, and must meet all AHEP0731 eligibility criteria at the time of emergent treatment. Patient must be enrolled on AHEP0731 prior to initiating protocol therapy. Per protocol, a patient will be ineligible if any chemotherapy is administered prior to AHEP0731 enrollment. If the patient receives AHEP0731 chemotherapy PRIOR to undergoing a diagnostic biopsy, pathologic review of material obtained in the future during either biopsy or surgical resection must either confirm the diagnosis of hepatoblastoma or not reveal another pathological diagnosis to be included in the analysis of the study aims. Patients will be staged for Risk Classification and Treatment at diagnosis using COG Staging Guidelines, as listed in the protocol. At the time of study enrollment, the patient[Single Quote]s treatment regimen must be identified. If the patient[Single Quote]s primary tumor was resected prior to the day of enrollment and a blood specimen for the determination of serum alpha-fetoprotein was not obtained prior to that surgery, the patient will be considered to have alpha-fetoprotein of greater than 100 ng/mL for the purpose of treatment assignment. If tumor samples obtained prior to the date of enrollment were not sufficient to determine whether small cell undifferentiated (SCU) histology was present, treatment assignment will be made assuming SCU is not present in the tumor. For patients with Stage I or II disease, specimens for rapid central review have been submitted and the rapid central review diagnosis and staging must be available to be provided on the AHEP0731 Eligibility CRF. * Patients must have a performance status corresponding to ECOG scores of 0, 1, or 2 (Karnofsky for patients > 16 years of age and Lansky for patients <= 16 years of age). * Patients may have had surgical resection of some or all sites of hepatoblastoma prior to enrollment. * Organ function requirements are not required for enrolled patients who are Stage I, PFH and will not be receiving chemotherapy. * Adequate renal function defined as: Creatinine clearance or radioisotope GFR > 70 mL/min/1.73 m2 OR a serum creatinine based on age/gender as listed in the protocol. * For patients who will be assigned to protocol chemotherapy, adequate liver function defined as: Total bilirubin < 1.5 x upper limit of normal (ULN) for age, and SGOT (AST) or SGPT (ALT) < 10 x ULN for age. * For patients who will be assigned to protocol chemotherapy, adequate bone marrow function defined as: Absolute neutrophil count (ANC) > 750/[MICRO-SYMBOL]L, Platelet count > 75,000/[MICRO-SYMBOL]L * For intermediate- and high-risk patients who will be assigned to protocol chemotherapy, adequate cardiac function defined as: Shortening fraction >= 27% by echocardiogram, or Ejection fraction >= 47% by radionuclide angiogram (MUGA). Note: the echocardiogram (or MUGA) may be done within 28 days prior to enrollment. * All patients and/or their parents or legal guardians must sign a written informed consent. * All institutional, FDA, and NCI requirements for human studies must be met. Additional Eligibility Criteria for High-Risk Patients * Serum triglyceride level <= 300 mg/dL (<= 3.42 mmol/L) and serum cholesterol level <= 300 mg/dL (7.75 mmol/L) * Random or fasting blood glucose within the upper normal limits for age. If the initial blood glucose is a random sample that is outside of the normal limits, then a follow-up fasting blood glucose can be obtained and must be within the upper normal limits for age. * Adequate Pulmonary Function Defined as: * Normal pulmonary function tests (including DLCO) if there is clinical indication for determination (e.g. dyspnea at rest, known requirement for supplemental oxygen). Note: For patients who do not have respiratory symptoms or requirement for supplemental oxygen, PFTs are NOT required. * Adequate Neurologic Function Defined as: * Patients with seizure disorder may be enrolled if on non-enzyme inducing anticonvulsants and if seizures are well controlled. (See Appendix IV of protocol for a list of recommended non-enzyme inducing anticonvulsants). * Adequate Clotting Function Defined as: Prothrombin Time (PT) < 1.2 x ULN