Neurofibromatosis type-2-related schwannomatosis presenting as peripapillary hamartoma: report on a novel NF2 mutation.

Background: Neurofibromatosis type-2-related schwannomatosis (NF2-SWN, formerly neurofibromatosis type 2) is a rare genetic disorder marked by the development of multiple nervous system tumors.

Case presentation: We report a 21-month-old female patient who presented for left eye deviation. Upon examination, intermittent exotropia and a fundus mass were detected. Wide field fundus examination revealed the presence of a combined hamartoma involving the optic nerve and retina. This finding was supported by MRI highlighting the lesion's characteristics. The patient's father and other relatives on the paternal side displayed symptoms of NF2-SWN, evident through the presence of acoustic neuroma, although they did not exhibit any ocular symptoms. DNA analysis revealed a novel loss-of-function mutation in exon 15 of the NF2 gene (NM_000268.3: c.1627_1628del, p.Lys543Aspfs *21) in both the patient and her father at a heterozygous state. By the age of three, her vision worsened, and optical coherence tomography showed vitreomacular traction and intraretinal fluid surrounding the lesion.

Conclusion: This case underscores the need to consider NF2- SWN in peripapillary hamartoma diagnoses and highlights the importance of genetic testing for early detection and management.