What are the signs and symptoms of Neurofibromatosis type 1? People affected by neurofibromatosis type 1 (NF1) have an increased risk of developing many different types of tumors (both cancerous and noncancerous). Almost all people with NF1 have neurofibromas, which are benign tumors that can affect nearly any nerve in the body. Most will develop these tumors on or just underneath the skin; however, neurofibromas can also grow in other places in the body and may even affect multiple nerves. Malignant peripheral nerve sheath tumors, which also grow along the nerves throughout the body, are the most common cancerous tumor found in people with NF1 and occur in approximately 10% of affected people. In children with NF1, the most common tumors are optic glioma (tumors that grow along the nerve leading from the eye to the brain) and brain tumors. Optic gliomas associated with NF1 are often asymptomatic although they can lead to vision loss. Other features of NF1 may include: Caf au lait spots (flat patches on the skin that are darker than the surrounding area) Freckling, especially in the underarm and groin Lisch nodules (clumps of pigment in the colored part of the eye that do not interfere with vision) Learning disabilities Seizures Autism spectrum disorder High blood pressure Short stature An unusually large head (macrocephaly) Skeletal abnormalities such as scoliosis GeneReview's Web site offers more specific information about the features of NF1. Please click on the link to access this resource. The Human Phenotype Ontology provides the following list of signs and symptoms for Neurofibromatosis type 1. If the information is available, the table below includes how often the symptom is seen in people with this condition. You can use the MedlinePlus Medical Dictionary to look up the definitions for these medical terms. Signs and Symptoms Approximate number of patients (when available) Cafe-au-lait spot 100% Lisch nodules 95% Benign neoplasm of the central nervous system 90% Generalized hyperpigmentation 90% Hypermelanotic macule 90% Kyphosis 90% Melanocytic nevus 90% Multiple lipomas 90% Neoplasm of the skin 90% Attention deficit hyperactivity disorder 50% Freckling 50% Hearing impairment 50% Heterochromia iridis 50% Incoordination 50% Memory impairment 50% Migraine 50% Neurological speech impairment 50% Paresthesia 50% Proptosis 50% Skeletal dysplasia 50% Slender long bone 50% Short stature 31% Plexiform neurofibroma 30% Specific learning disability 30% Abnormality of the respiratory system 7.5% Arterial stenosis 7.5% Glaucoma 7.5% Hydrocephalus 7.5% Hypertension 7.5% Hypopigmented skin patches 7.5% Leukemia 7.5% Limitation of joint mobility 7.5% Macrocephaly 7.5% Neoplasm of the gastrointestinal tract 7.5% Neuroendocrine neoplasm 7.5% Precocious puberty 7.5% Sarcoma 7.5% Scoliosis 7.5% Seizures 7.5% Tall stature 7.5% Urinary tract neoplasm 7.5% Visual impairment 7.5% Tibial pseudoarthrosis 4% Aqueductal stenosis 1.5% Genu valgum 1.5% Hypsarrhythmia 1.5% Optic glioma 1.5% Renal artery stenosis 1.5% Spinal neurofibromas 1.5% Meningioma 1% Pheochromocytoma 1% Astrocytoma - Autosomal dominant inheritance - Axillary freckling - Hypertelorism - Inguinal freckling - Intellectual disability, mild - Neurofibrosarcoma - Overgrowth - Parathyroid adenoma - Rhabdomyosarcoma - Spina bifida - The Human Phenotype Ontology (HPO) has collected information on how often a sign or symptom occurs in a condition. Much of this information comes from Orphanet, a European rare disease database. The frequency of a sign or symptom is usually listed as a rough estimate of the percentage of patients who have that feature. The frequency may also be listed as a fraction. The first number of the fraction is how many people had the symptom, and the second number is the total number of people who were examined in one study. For example, a frequency of 25/25 means that in a study of 25 people all patients were found to have that symptom. Because these frequencies are based on a specific study, the fractions may be different if another group of patients are examined. Sometimes, no information on frequency is available. In these cases, the sign or symptom may be rare or common.