Segmental neurofibromatosis in childhood

Segmental neurofibromatosis refers to individuals who have manifestations of neurofibromatosis type 1 (NF‐1) limited to one area of the body. It results from a post‐conceptional mutation in the NF‐1 gene leading to somatic mosaicism. Although it is generally considered a rare condition, this report of 39 children with segmental NF‐1 demonstrates that it is commonly seen in a pediatric NF‐1 referral center. The mean age at diagnosis was 7.8 years (range: 2–25 years). Twenty‐nine patients had only pigmentary manifestations of segmental NF‐1, including seven who had only café‐au‐lait macules and 22 who had café‐au‐lait macules and freckling. Two patients had isolated plexiform neurofibromas; a third patient had a plexiform neurofibroma of the eyelid in addition to ipsilateral dysplasia of the sphenoid wing and Lisch nodules. A 12‐year‐old girl had an isolated tibial pseudarthrosis. An 8‐year‐old boy had an isolated optic pathway tumor, which behaved both biologically and radiographically as an NF1‐associated tumor. While most children with segmental NF‐1 have only localized pigmentary changes, some children will have isolated plexiform neurofibromas, pseudarthroses, or optic pathway tumors. Accurate diagnosis of segmental NF‐1 is crucial for both management and genetic counseling. © 2003 Wiley‐Liss, Inc.