Asymmetric Inferior Predilection of Lisch Nodules With Unilateral Ptosis

Lisch nodules are melanocytic hamartomas that have been hypothesized to grow larger in the presence of sunlight. A 17-year-old boy with neurofibromatosis Type 1 and congenital ptosis in one eye presented and was found to have a distinct asymmetry of Lisch nodules between eyes with less under the ptotic lid. This case supports the theory that Lisch nodules form at least partially due to a direct trophic effect of sunlight.

Photo Essay Section Editors: Melissa W. Ko, MD Dean M. Cestari, MD Asymmetric Inferior Predilection of Lisch Nodules With Unilateral Ptosis Robert A. Egan, MD FIG. 1. A. Right eye showing copper-yellow Lisch nodules that are present 360° around the pupil, although with a mild inferior predilection. B. Left eye, the eye with the ptotic eyelid, showing approximately half the number of Lisch nodules and most located inferiorly. Abstract: Lisch nodules are melanocytic hamartomas that have been hypothesized to grow larger in the presence of sunlight. A 17-year-old boy with neurofibromatosis Type 1 and congenital ptosis in one eye presented and was found to have a distinct asymmetry of Lisch nodules between eyes with less under the ptotic lid. This case supports the theory that Lisch nodules form at least partially due to a direct trophic effect of sunlight. Journal of Neuro-Ophthalmology 2020;40:106 doi: 10.1097/WNO.0000000000000836 © 2019 by North American Neuro-Ophthalmology Society A 17-year-old boy with neurofibromatosis type 1 (NF1) was referred to rule out papilledema due to hydrocephalus. He complained of lifelong ptosis of the left eye. His neuro-ophthalmic examination was normal with the exception of his irides, which displayed Lisch nodules bilaterally with an inferior predilection. However, the iris under the congenitally ptotic left lid demonstrated no more than half Departments of Neurology and Ophthalmology, MultiCare Rockwood Clinic, Spokane, Washington. The author reports no conflicts of interest. of the Lisch nodules when compared with the normal right eye (Fig. 1). Lisch nodules are raised melanocytic hamartomas found on the iris of patients with NF1. There is some debate on whether they are found more commonly on the inferior portion of the iris. (1,2) A previous patient with NF1 and bilateral congenital ptosis showed a stronger inferior predilection of Lisch nodules (3) potentially related to less sunlight striking the upper half of the patient's irides. If sunlight had no effect on the generation of Lisch nodules, then a patient with longstanding monocular ptosis and NF1 should display bilaterally equal Lisch nodules. This patient demonstrated a marked asymmetry of Lisch nodules with inferior predilection supporting the idea that sunlight may have a direct trophic effect on their development. REFERENCES 1. Nichols JC, Amato JE, Chung SM. Characteristics of Lisch nodules in patients with neurofibromatosis type 1. J Pediatr Ophthalmol Strabismus. 2003;40:293-296. 2. Ragge NK, Falk RE, Cohen WE, Murphree AL. Images of Lisch nodules across the spectrum. Eye (Lond). 1993;7:95-101. 3. Wood TD, Egan RA. Inferior predilection of Lisch nodules with ptosis. Neurology. 2005;64:1370. This report did not require approval by the Oregon Health and Science University Institutional Review Board where this study was undertaken. Address correspondence to Robert A. Egan, MD, MultiCare Rockwood Clinic, 910 W 5th Avenue, Suite 1000, Spokane, WA 99204; E-mail: [e-mail] 106 Egan: J Neuro-Ophthalmol 2020; 40: 106 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited.