Pirfenidone in Treating Young Patients With Neurofibromatosis Type 1 and Plexiform Neurofibromas

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