Inclusion Criteria

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