People affected by more severe variants of NF-1 may have a shorter life expectancy if the disease is associated with CNS tumors or other malignancies, mental retardation, or severe seizures. In 1944, Sorenson and coworkers conducted a study of 212 affected patients in Denmark and found that patients with NF, particularly the more severe forms requiring hospitalization, have a poorer survival rate. NF tends to be progressive throughout life, with the number and the size of associated tumors increasing. The cutaneous manifestations of NF-1 are a prominent aspect of this disorder. They include hyperpigmentation, hypopigmentation, and cutaneous neurofibromas.
Hyperpigmentation can occur in focal or diffuse forms.
Focal hyperpigmentation also includes axillary and inguinal freckling. Hypopigmentation can occur in patients with NF-1. Abnormalities of CNS development are common. Similarly functional problems often are noted, and, of course, benign and malignant tumors of the CNS occur at a greatly increased incidence in NF-1. Abnormalities of CNS development Simple megalencephaly is common and generally harmless.