Background: Segmental neurofibromatosis type 1 (NF-1) has the characteristic features of generalized NF-1 but is isolated to a particular segment of the body. Segmental NF-1 results from a postzygotic mutation during embryogenesis in the NF-1 gene on chromosome 17. The embryologic timing of the mutation and cell types affected predict the clinical phenotype.
Objective: We present a case of a 52-year-old woman with segmental neurofibromas isolated to the right cheek and neck. We review the recent literature on the genetic and cellular differences between the various clinical manifestations of segmental NF-1.
Methods: A MEDLINE search for cases of segmental neurofibromatosis was conducted.
Results: In patients with segmental NF-1 presenting as neurofibromas-only, the distribution follows a neural distribution in dermatomes because the genetic mutation appears to be limited to Schwann cells. In patients with pigmentary changes only, the NF-1 mutation has been shown to occur in fibroblasts and the distribution tends to follow the lines of Blaschko.
Conclusion: Our patient's neurofibromas were secondary to a postzygotic mutation in the NF-1 gene of neural crest-derived cells. This mutation most likely occurred later in embryogenesis in cells that had already differentiated to Schwann cells and were committed to the dermatomal distribution of the right neck and cheek region (C2).