Unusual fundus lesion in mosaic neurofibromatosis type 2

Neurofibromatosis is a neurocutaneous syndrome that predisposes individuals to a variety of tumors. In type 2, these typically do not present until early adulthood. We present a case of an unusual fundus lesion in neurofibromatosis type 2 (NF2) in a young child.

Case Report.

An 18-month-old girl presented to our clinic with a diagnosis of persistent fetal vasculature. She had abnormal brain anatomy on an MRI and underwent a left temporo-amygdalohippocampectomy at 13 months of age for epilepsy control. Genetic testing of the left-brain tissue showed a somatic NF2 gene mutation (c.774G>A) and a blood sample revealed a mosaic NF2 gene deletion (exons 11-14). Serial examinations under anesthesia revealed a stable transparent 0.5x0.5 mm flat lesion along the superotemporal arcade in the right fundus and a larger growing, white-colored lesion originating from the left optic nerve with surrounding subretinal fluid with an overlying fibrotic plaque and stalk protruding into the vitreous. She developed neovascular glaucoma and ultimately underwent left enucleation due to refractory pain. Histopathology showed an optic nerve sheath meningioma with intraocular extension.

Although ocular abnormalities in NF2 are a relatively rare finding in young children, this case shows that an optic nerve sheath meningioma can show intraocular extension and should be considered in the differential diagnosis for an intraocular mass.