Neurofibromatosis Type 1: Cutaneous Signs and Surveillance

Overview / Definition Neurofibromatosis Type 1 (NF1), also known as von Recklinghausen's disease, is an autosomal dominant genetic disorder caused by mutations in the NF1 gene on chromosome 17. It is characterized by the presence of multiple neurofibromas, café-au-lait macules, and other skin findings, along with potential neurological and orthopedic complications. Epidemiology NF1 affects approximately 1 in 3,000 individuals worldwide. It shows no preference for sex or ethnicity and is present from birth, often becoming clinically apparent in early childhood. Family history is significant, with about half of cases being due to new mutations. Pathophysiology / Mechanism The NF1 gene encodes a protein called neurofibromin, which is involved in regulating cell growth and differentiation. Mutations in this gene lead to a loss of function, resulting in uncontrolled proliferation of neural crest-derived cells, leading to the formation of neurofibromas and other tumors. Clinical Presentation The clinical manifestations of NF1 are diverse and can include: Café-au-lait spots: Light brown macules, typically present at birth or during early childhood. Neurofibromas: Soft, benign tumors that can be found on the skin or deeper tissues, often appearing in adolescence. Axillary or groin freckling: Freckling in specific areas is common. Lisch nodules: Iris hamartomas that appear as brown spots on the iris. Bone abnormalities: Scoliosis, tibial dysplasia, and other orthopedic issues may occur. It is important to note that not all individuals with NF1 will exhibit all these signs, and the severity can vary significantly. Diagnosis / Workup The diagnosis of NF1 is primarily clinical, based on the presence of characteristic findings. The following criteria are used: At least two café-au-lait macules. At least two neurofibromas or one plexiform neurofibroma. Freckling in the axillary or groin area. At least two Lisch nodules. A first-degree relative with NF1. Genetic testing can confir