Case report
A 9-year-old boy, with a history of HLH from 6 months ago, was referred by his pediatric oncologist to the ophthalmic emergency department with a complaint of painless progressive blurred vision in his right eye. On ocular external examination, there was a mild conjunctival injection, chemosis, and proptosis in his right eye (Figure 1). The best-corrected distance visual acuity was 20/40 and 20/20 for his right and left eye respectively. The relative afferent pupillary defect (RAPD) examination was positive for the right eye. Anterior segment examination was unremarkable for both eyes. In the fundus examination, we found an optic disc swelling and peripapillary hemorrhage in the right eye. The left fundus examination showed a mild optic nerve head blurred margin. Regarding the patient’s clinical status, differential diagnoses include neoplastic infiltrative optic neuropathy, cytomegalovirus (CMV) optic neuritis, drug toxicity, and CNS involvement with increased intracranial pressure (ICP). For further evaluation, a brain and orbital MRI with gadolinium enhancement (Figure 3), aqueous sampling with a 25-gauge needle for polymerase chain reaction (PCR) to detect CMV, lumbar puncture (LP) to analyze cerebrospinal fluid cytology and biochemistry, and also for ICP measurement, and blood test for hematology and biochemistry were ordered. We summarized the results of the patient’s imaging and lab tests in Table 1.