Supplementary Material for: Hemophagocytic Lymphohistiocytosis in Adults with Intraocular Involvement: Clinicopathologic Features of 3 Cases

Background/Aims: Hemophagocytic lymphohistiocytosis (HLH) is an infrequent inflammatory multisystemic syndrome. Only rare cases with ophthalmic involvement describing their pathologic features have been previously reported. Methods: We report 3 cases of adult-onset HLH with bilateral ocular involvement and describe their clinicopathologic features. Results: Three adult males - 2 with a history of viral infection - developed persistent fever, fatigue, bone marrow abnormalities, and irreversible multiorgan failure. Visual impairment was also documented in 2 cases. Complete autopsies were performed. Ophthalmic pathology demonstrated a bilateral histiocytic infiltrate with scant lymphocytes affecting the uvea. Focal extension to the retina, optic nerve, and trabecular meshwork were also identified, as well as hemophagocytosis in 1 case. Macrophages showed strong immunoreactivity for CD163 antibody and lacked BRAF p.V600E mutant protein. Conclusion: HLH is an unusual disorder associated with several systemic conditions. Histologic features in the eye are poorly documented, with prior reports restricted to children. Our 3 adult cases are reported using updated criteria and, despite the difference in age, show changes similar to those observed in the pediatric population.