Unilateral Lisch Nodules in a 47-year-old Woman Without Other Stigmata of Neurofibromatosis Type I: An Example of Segmental Neurofibromatosis?

A 47-year-old woman, with no personal or familial history of Neurofibromatosis type 1 (NF1) or 2, was referred for evaluation of left unilateral Lisch nodules (LN) discovered through a routine eye care performed one month before (Figure 1a and b). Fundus oculi evaluation was normal in both eyes. The patient had occasionally attended routine eye examinations since her childhood, without discovering anomalies. Her past medical history was remarkable for migraine with aura, essential hypertension, and mild hypercholesterolemia. No other NF1 stigmata were noticed with the exception of one very pale 1.0 � 1.0cm cafe`au-lait spot below the left leg. Magnetic resonance imaging of brain and spine, cardiac and abdominal ultrasound findings were unremarkable. The term segmental NF1 is used when the NF1 stigmata are confined to one or more body segments because of somatic mosaicism for the NF1 gene. Segmental NF1 is estimated to be rarer than the fullblown phenotype, with a prevalence of 1 in 36–40,000 subjects. 1 In patients with segmental form, the involved parts of the body may develop all the manifestations with the same chronological order as they appear in the generalized phenotype. 2