[Segmental neurofibromatosis].

Segmental neurofibromatosis is a rare form of the disease characterized by the unilateral location of cutaneous neurofibromas and café au lait spots along one or several dermatomes. It corresponds to the fifth type in Riccardi's classification. We report the 83rd case of segmental neurofibromatosis discovered by chance in an 83-year old woman presenting with isolated cutaneous neurofibromas situated on the right T10-L1 dermatomes. Type five neurofibromatosis is divided into four subgroups according to the uni- or bilateral site of the lesions, the presence or absence of a family history and the association, or lack of, with deep regional or systemic lesions. It is usually not hereditary, but due to a post-zygotic somatic mutation in the primary neural crest. The disease has a favourable prognosis: no case of evolution towards generalized neurofibromatosis has ever been reported.