Segmental neurofibromatosis.

Segmental neurofibromatosis is characterised by a limited, segmental distribution of cutaneous neurofibromatosis type 1 (NF1) lesions. It has been suggested that segmental NF results from a postzygotic NF1 gene mutation, and, recently, this hypothesis has been proven in a patient with regionally distributed café-au-lait (CAL) spots and freckles by demonstrating an NF1 microdeletion restricted to fibroblasts cultured from CAL spots. We describe here a patient with segmental NF in which we could not demonstrate any NF1 gene mutation in fibroblasts cultured from neurofibromas by use of the protein truncation test, enzymatic mutation detection and fluorescence in situ hybridisation. These data are in line with the concept that NF1 mutations in Schwann cells, but not in fibroblasts, correlate with neurofibroma formation.