19.1 Introduction
Neurocutaneous syndromes consist of neurologic issues in addition to cutaneous findings. One of the most common neurocutaneous disorders, which may be identified in the adolescent age group, is neurofibromatosis. Adolescents with neurofibromatosis are predisposed to both benign and malignant tumors.
19.2 Epidemiology
Neurofibromatosis 1 (NF1) occurs in approximately 1:2500–1:3000 individuals. NF1 occurs as a result of a germline mutation in one of the two alleles of the tumor suppressor gene NF1 on chromosome 17q11.2 (Ly KI et al). Neurofibromatosis 2 (NF2) is less common than NF1, occurring in 1:25,000 individuals. The mutation associated with NF2 occurs in neurofibromin-2 on chromosome 22q12. Patients with NF2 have acoustic neuromas – most typically bilateral. Inheritance of both NF1 and NF2 is considered to be autosomal dominant; however, the rate of spontaneous mutations is approximately 50% for both.
19.3 Clinical Findings
Cutaneous manifestations are significant in NF1. They represent the majority of the diagnostic criteria. The cutaneous findings with NF2 are less prominent. The most common cutaneous finding in NF1 is a café-au-lait macule (CALM) (Fig. 19.1). In skin of color, the café’-au-lait macules will be darker in color (Fig. 19.2). Other cutaneous findings, which are part of the diagnostic criteria, are neurofibromas, freckling of skin folds (Fig. 19.3), Lisch nodules, and plexiform neuromas. Plexiform neuromas have an increased risk of transformation into a malignant peripheral nerve sheath tumor (MPNST).
Other tumors noted are rhabdomyosarcomas.
Other associated findings with NF1 are pruritus, macrocephaly, learning disabilities, and skeletal abnormalities (short stature, osteopenia, scoliosis, and sphenoid wing dysplasia).
As mentioned above, NF2 has less prominent cutaneous findings when compared to NF1. Associated findings with NF2 are meningiomas of the brain, and schwannomas of the dorsal roots of the spinal cord.
Multiple neurofibromas with a CALM in the upper part of the photograph in a patient with NF1
CALM which is a more brown in skin of color
Axillary freckling in a patient with NF1
19.4 Laboratory
Genetic testing may be indicated when the diagnostic criteria are not confirmatory or mosaicism is suspected. Tumor surveillance is an ongoing issue. Radiation therapy is to be avoided in NF1 patients due to the increased risk of developing radiation-induced malignancies [1].
19.5 Treatment
In light of the predisposition for tumors, health supervision includes tumor surveillance especially if specific findings are noted. Tumor-specific treatment may include surgical excision and/or chemotherapy. As noted above, radiation therapy is used with caution [2].
19.6 Prognosis
Life expectancy is shortened due to malignancy and has been estimated between 54 and 71.5 years [3].