Unilateral Yasunari Nodule-Like Appearance in a Patient Without Neurofibromatosis Type 1

Yasunari nodules are choroidal lesions characterized by bright, poorly demarcated multiple lesions detected through near-infrared reflectance imaging and are considered diagnostic for neurofibromatosis type 1 (NF1). We report a case of unilateral Yasunari-like nodules in a patient without clinical or genetic evidence of NF1.

A 53-year-old male presented with a 7-day history of floaters in both eyes. Best-corrected visual acuity was 20/20 in the right eye and 20/25 in the left eye. Slit-lamp examination revealed bilateral multiple iris nevi. Both fundi appeared normal on colour photography. The right infrared image demonstrated multiple bright, relatively well-defined areas suggesting Yasunari nodules, whereas the left infrared image was normal. Green and blue autofluorescent images were unremarkable bilaterally. Spectral domain optical coherence tomography revealed poorly demarcated hyperreflective choroidal nodule-like changes in the right eye only. Physical examination revealed no signs of NF1. Next-generation deoxyribonucleic acid sequencing of blood and skin specimens was negative for NF1.

This is the second reported case of unilateral Yasunari-like nodules in a patient without NF1. Despite extensive clinical and genetic evaluation, including testing for somatic mosaicism, all results were negative for NF1. The lesions were considered benign incidental findings and monitored conservatively.

Although infrequent, lesions resembling Yasunari nodules may be observed in patients without NF1. Clinicians should be aware of this possibility when encountering similar imaging findings.

Clinicians should be aware of the fact that, although the presence of choroidal nodules (Yasunari nodules) is pathognomonic for the diagnosis of neurofibromatosis type I, similar choroidal appearances may occasionally be observed in normal eyes on infrared imaging.