The diagnostic histopathologic features of ocular malaria

Abstract

Background: The ocular complications in patients with malaria have been studied clinically by many investigators, but the histopathologic changes were rarely described and generally regarded as nonspecific.

Methods: The eye of a 53-year-old man who died of chloroquine-resistant Plasmodium falciparum malaria was studied by brightfield and polarized light microscopy.

Findings: An epibulbar hemorrhage that involved the conjunctiva, episclera, and tendinous insertion of the medial rectus muscle was present. Cytoadherence and rosetting of the parasitized erythrocytes were observed within the partially occluded lumens of small retinal and uveal blood vessels. The birefringence of hemozoin (malarial pigment) within the lumens of small ocular blood vessels and in the hemorrhagic epibulbar area was demonstrated by polarized light.

Conclusion: Birefringent hemozoinemia in vascular lumens of ocular tissues indicates systemic malarial infestation by any of the four species of malaria. Cytoadherence and rosetting of the parasitized erythrocytes inside ocular capillaries and venules is diagnostic of P. falciparum and is an important cause of ocular hemorrhage.