[Segmental neurofibromatosis and germ-line mosaicism]

Segmental neurofibromatosis, also designated "NF-V" according to Riccardi's classification, should be considered a mosaic manifestation of one of the other types of neurofibromatosis, mostly of NF-I. Irrespective of the site and size of the body area affected, the patients are always at risk of germ-line mosaicism and they may therefore transmit the phenotype, but not the mosaic, to the next generation. Hence it follows that segmental neurofibromatosis does not constitute a distinct entity, and it is not reasonable to discriminate unilateral from bilateral or "hereditary" from "nonhereditary" forms.