Incidental (malignancy) and coincidental (idiopathic polydactylous longitudinal erythronychia) conditions in patients with segmental neurofibromatosis.

Segmental neurofibromatosis (SNF) is an uncommon presentation of neurofibromatosis type 1 (NF-1). Although patients with SNF are at a lower risk for developing NF-l-associated complications, the estimated occurrence of related malignancies may be approaching the frequency observed in patients with NF-1. Idiopathic polydactylous longitudinal erythronychia also may be associated with SNF, though the frequency of this association remains to be determined.