DISEASE CHARACTERISTICS:

• Diagnosis of neurofibromatosis type 1 (NF1) AND

• Plexiform neurofibromas

  • Neurofibromas that have grown along the length of a nerve and may involve multiple fascicles and branches (spinal neurofibromas involve 2 or more levels with connection between the levels or extending laterally along the nerve)

  • Potential to cause significant morbidity such as:

    • Head and neck lesions that could compromise airway or great vessels
    • Brachial or lumbar plexus lesions that could cause nerve compression and loss of function
    • Lesions that could result in major deformity (e.g., orbital lesions) or significant cosmetic problems
    • Lesions of the extremity that cause limb hypertrophy or loss of function
    • Painful lesions

• Meets at least 1 other diagnostic criteria for NF1

  • 6 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
  • 2 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

• Measurable plexiform neurofibromas

  • At least 3 cm in 1 dimension
  • Tumor resection not feasible
• No history of malignant peripheral nerve sheath tumor or other cancer
• No evidence of an active optic glioma requiring chemotherapy or radiotherapy
• No malignant glioma

PATIENT CHARACTERISTICS:

Age

• 3 to 21

Performance status

• Karnofsky 50-100% (over 10 years of age)
• Lansky 50-100% (10 years and under)

Life expectancy

• Not specified

Hematopoietic

• Absolute granulocyte count at least 1,500/mm^3
• Hemoglobin at least 9.0 g/dL
• Platelet count at least 150,000/mm^3

Hepatic

• Bilirubin normal
• SGPT no greater than 2 times upper limit of normal
• No clinically significant hepatic dysfunction that would preclude study participation

Renal

• Creatinine normal for age OR
• Creatinine clearance at least 70 mL/min

Cardiovascular

• No clinically significant cardiac dysfunction that would preclude study participation

Pulmonary

• No clinically significant pulmonary dysfunction that would preclude study participation

Other

• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception during and for 2 months after study
• Must be able to take pirfenidone orally
• No serious infections
• No clinically significant unrelated systemic illness or organ dysfunction that would preclude study participation

PRIOR CONCURRENT THERAPY:

Biologic therapy

• At least 30 days since prior immunotherapy
• No concurrent immunotherapy
• No concurrent hematopoietic growth factors

Chemotherapy

• At least 30 days since prior chemotherapy
• No concurrent chemotherapy directed at the tumor

Endocrine therapy

• At least 30 days since prior hormonal therapy directed at the tumor
• No concurrent hormonal therapy directed at the tumor

Radiotherapy

• At least 90 days since prior radiotherapy to the site of the plexiform neurofibroma
• No concurrent radiotherapy directed at the tumor

Surgery

• Not specified

Other

• Recovered from prior therapy
• More than 30 days since prior investigational agents
• No prior pirfenidone
• No other concurrent investigational agents