Imatinib Mesylate in Treating Patients With Recurrent Ewing's Family of Tumors or Desmoplastic Small Round-Cell Tumor

DISEASE CHARACTERISTICS: Diagnosis of Ewing's family of tumors OR desmoplastic small round-cell tumor Must have immunohistochemical evidence of expression of greater than 2+/4+ for either Kit (CD117) or platelet-derived growth factor receptor -a or -b No symptomatic brain metastases Asymptomatic brain metastases are allowed provided patient is not on concurrent anticonvulsants or corticosteroids PATIENT CHARACTERISTICS: Age Over 16 Performance status ECOG 0-2 Life expectancy Not specified Hematopoietic Absolute neutrophil count greater than 1,500/mm^3 Platelet count greater than 100,000/mm^3 Hemoglobin greater than 9 g/dL Hepatic Bilirubin less than 1.5 times upper limit of normal (ULN) SGOT and SGPT less than 2.5 times ULN No chronic active hepatitis No cirrhosis No other acute or known chronic liver disease Renal Creatinine less than 1.5 times ULN Cardiovascular No concurrent poorly controlled or severe cardiovascular disease Pulmonary No concurrent poorly controlled or severe pulmonary disease Other HIV negative No concurrent poorly controlled or severe central nervous system disease No other concurrent poorly controlled or severe nonmalignant disease PRIOR CONCURRENT THERAPY: Biologic therapy Not specified Chemotherapy At least 3 weeks since prior chemotherapy Endocrine therapy See Disease Characteristics Radiotherapy At least 3 weeks since prior radiotherapy Surgery More than 2 weeks since prior major surgery Other More than 28 days since prior investigational agents