Clinical approach to a child with hemophagocytic lymphohistiocytosis and bilateral optic nerve head infiltration: A case report and brief literature review.

Key Clinical Message: Infiltrative optic neuropathy in hemophagocytic lymphohistiocytosis is rare but could potentially lead to visual loss. Cytomegalovirus (CMV) optic neuritis, drug toxicity, and CNS involvement with increased intracranial pressure (ICP) are differential diagnoses that have to be considered. Abstract: In this report, we introduced a known case of hemophagocytic lymphohistiocytosis (HLH) with progressive visual loss due to bilateral optic nerve head (ONH) involvement. A 9-year-old boy with a history of HLH from 6 months ago was referred to the ophthalmic emergency department with a complaint of painless progressive blurred vision in his right eye. The fundus examination found an optic disc swelling and peripapillary hemorrhage in the right eye. The left fundus examination showed a mild ONH blurred margin. Systemic evaluations including brain and orbital MRI with gadolinium enhancement and CSF analysis showed optic nerve and brain involvement with tumoral cells. Despite systemic chemotherapy with etoposide, the disease had a progressive course so in the last follow-up visit, fundus examination revealed disc swelling, retinal edema, and epiretinal hemorrhage in both eyes and visual acuity deteriorated to no light perception and counting fingers in the right and left eye, respectively. ONH involvement in HLH is rare but could be sight-threatening. Differential diagnoses that should be investigated include neoplastic infiltrative optic neuropathy, cytomegalovirus (CMV) optic neuritis, drug toxicity, and CNS involvement with increased intracranial pressure (ICP).