Discussion
In this study, we reported a child with HLH presented to us with bilateral painless progressive visual loss. In the ophthalmic examination, we found bilateral optic disc swelling and hemorrhage. HLH is an immune system dysregulation characterized by multiorgan infiltration of macrophages, especially affecting the liver, spleen, lungs, bone marrow, lymph nodes, and kidneys, leading to various signs and symptoms. The mean age of occurrence is 1.8 in children and 50 years old in adults(1).
Ocular involvement is uncommon in HLH. Wang et al., in a study in 2023, showed that old age, autoimmune disorders, and decreasing RBC and platelet counts are independent risk factors of ocular involvement in HLH(2). Retinal hemorrhage, conjunctivitis, corneal infiltration, anterior uveitis, papillitis, and choroidal involvement are the main ophthalmic signs in these patients(2). A literature review regarding ocular involvement in HLH is briefed in Table 2.
Optic nerve head involvement in HLH is rare. A wide range of differential diagnoses should be considered(3). We summarized the clinical approach to our patient in Figure 4. Regarding the patient’s immune status, opportunistic infections such as CMV must be investigated and ruled out. Ocular involvement in CMV infection is a serious sight-threatening condition that could be manifested as optic nerve head inflammation(4). The sensitivity and specificity of PCR tests for aqueous samples are 82% and 91%, respectively. The result of the aqueous and blood PCR tests was negative in our patient and we found no evidence of systemic CMV infection. In the brain and orbital MRI, we found bilateral optic nerve infiltration and the CSF analysis showed the brain involvement with tumoral cells. However, ICP was within normal limits. Another differential diagnosis in this patient is an adverse drug complication. There are reports of etoposide-related optic nerve toxicity(5). However, clinical evidence and imaging findings indicate optic neuropathy due to tumoral infiltration, not drug toxicity.