Inclusion Criteria:

- Diagnosis of neurofibromatosis type I, based on clinical criteria (NIH Consensus
Development Conference, 1988). Tumors will not be confirmed histologically, since the
biopsy could cause a change in tumor growth and such interfere with effect of
Pirfenidone treatment.

- Male or female patients

- Age 18 years old

- All patients should be mentally capable of signing the consent form or should have a
legal guardian to provide consent

- Patients who are experiencing symptoms from neurofibromatous lesions and who refuse
surgery or are not good surgical candidates, such as those with plexiform
neurofibroma who are experiencing significant discomfort, disfigurement or nerve
compression or

- Presence of multiple spinal neurofibromas in which the surgical removal would carry a
major risk for spinal cord damage.

Exclusion Criteria:

- Tumors for which surgical removal could lead to permanent (or long-term) relief of
symptoms

- Patients with open skin lesions and patients for whom surgery is being contemplated
or who had surgery less than 4 weeks from starting treatment

- Patients for whom biopsy is warranted for suspected malignancies

- Individuals younger than 18 years

- Pregnant and lactating women

- Inability to have MR imaging (e.g. claustrophobia, pacemaker or allergy to contrast
dye, if administration is needed for neurofibroma imaging)