Imatinib Mesylate in Treating Patients With Relapsed or Refractory Solid Tumors of Childhood

Inclusion Criteria: * Histologically confirmed solid tumors including the following: * Ewing's sarcoma * Bone or soft tissue primitive neuroectodermal tumor * Osteosarcoma * Neuroblastoma * Desmoplastic small round cell tumor * Synovial cell sarcoma * Gastrointestinal stromal tumor (GIST) * Metastatic pulmonary disease eligible * No pleural effusion of any size or definite radiologic evidence of pleural-based disease * Recurrent or refractory to conventional therapy * GIST eligible at initial presentation * Tumor tissue blocks must be available * At least 1 measurable lesion * At least 20 mm by conventional techniques * At least 10 mm by spiral CT scan * Lesions assessable only by radionuclide scan are not considered measurable * Performance status - Lansky 50-100% (≤ 10 years of age) * Performance status - Karnofsky 50-100% (\> 10 years of age) * At least 2 months * Absolute neutrophil count ≥ 1,000/mm\^3\* * Platelet count ≥ 75,000/mm\^3\* (transfusion independent) * Hemoglobin ≥ 8.0 g/dL\* (RBC transfusions allowed) * Bilirubin ≤ 1.5 times upper limit of normal (ULN) * ALT ≤ 2.5 times ULN * INR \< 1.5 * PTT ≤ ULN * Fibrinogen ≥ lower limit of normal * Creatinine normal for age * Glomerular filtration rate ≥ 70 mL/min * No uncontrolled infection * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective barrier contraception * At least 1 week since prior biologic therapy or immunotherapy and recovered * At least 1 week since prior growth factors * No concurrent immunomodulating agents * At least 2 weeks since prior myelosuppressive chemotherapy (4 weeks for nitrosoureas) and recovered * No concurrent chemotherapy * No concurrent steroids * Recovered from prior radiotherapy * At least 2 weeks since prior local palliative radiotherapy (small port) * At least 3 months since prior craniospinal radiotherapy or radiotherapy to 50% or more of pelvis * At least 6 weeks since other prior substantial bone marrow radiation * No concurrent radiotherapy during first course of treatment * Concurrent palliative radiotherapy to local painful lesions allowed after first course of treatment provided there is no evidence of disease progression and at least 1 measurable lesion remains outside radiation port * No concurrent therapeutic doses of warfarin * No concurrent anticonvulsants that induce the cytochrome p450 enzyme system (e.g., phenytoin, carbamazepine, and phenobarbital) * Concurrent benzodiazepines and gabapentin allowed * Concurrent low-molecular weight heparin allowed