DISEASE CHARACTERISTICS:

• Diagnosis of progressive, debilitating, severely disfiguring, or life-threatening plexiform neurofibroma (PN) that is surgically unresectable (or surgery refused by patient) and for which there is no other standard medical management

  • Histologic confirmation of tumor not required in the presence of consistent clinical and radiographic findings

    • Tumor must be biopsied if any clinical observation or scan suggests possible malignant transformation

• Measurable disease

  • PN lesion that can be measured in at least 2 dimensions by direct physical examination (clinical measurement and serial photography) or MRI

• Recurrent or progressive disease as documented by an increase in size or the presence of new lesions on MRI

  • Appearance of new tumors or a measurable increase in the sum of the product of the two longest perpendicular diameters of the index lesion(s) over a time period of no more than 12 months prior to study entry

• Must meet at least one other diagnostic criteria for neurofibromatosis type 1 (NF1):

  • Six or more cafe-au-lait spots at least 0.5 cm in prepubertal patients or at least 1.5 cm in postpubertal patients
  • Freckling in the axilla or groin
  • Optic glioma
  • Two or more Lisch nodules
  • Distinctive bony lesion (dysplasia of the sphenoid bone or dysplasia or thinning of long bone cortex)
  • First-degree relative with NF1
• Prior therapy for NF1 or PN is not required

PATIENT CHARACTERISTICS:

Age:

• 25 and under

Performance status:

• Lansky 60-100% OR
• Karnofsky 60-100%

Life expectancy:

• At least 12 months

Hematopoietic:

• CBC normal

  • Absolute neutrophil count greater than 1,000/mm^3
  • Platelet count greater than 100,000/mm^3

Hepatic:

• Bilirubin no greater than 1.5 times normal
• ALT/AST no greater than 1.5 times normal

Renal:

• BUN no greater than 1.5 times normal
• Creatinine no greater than 1.5 times normal

Other:

• Not pregnant or nursing
• Negative pregnancy test

PRIOR CONCURRENT THERAPY:

Biologic therapy:

• At least 1 week since prior filgrastim (G-CSF)
• No concurrent immunotherapy

Chemotherapy:

• At least 4 weeks since prior chemotherapy
• No other concurrent chemotherapy

Endocrine therapy:

• No concurrent hormonal therapy directed at the tumor

Radiotherapy:

• At least 6 weeks since prior radiotherapy
• No concurrent radiotherapy

Surgery:

• See Disease Characteristics

Other:

• Recovered from any prior therapy
• At least 30 days since prior investigational agents