Bilateral Toxoplasma Retinochoroiditis Simulating Cytomegalovirus Retinitis in an Allogeneic Bone Marrow Transplant Patient

A 36-year old female with acute myelogenous leukemia presented with a sudden decrease in vision one month following bone marrow transplantation (BMT). She had been taking multiple immunosuppressants to treat her recently-developed graft-versus-host-disease (GVHD). Visual acuity was 20/60 in her right eye and 20/25 in her left. Ophthalmic examination revealed mild inflammatory reaction in both the anterior chamber and the vitreous of both eyes, as well as densely opaque yellow-white infiltrates with well-demarcated borders in the posterior retina of both eyes. She was originally diagnosed as CMV retinitis, but treatment with ganciclovir failed to improve her ocular condition. Subsequent work-up, including serology and brain MRI, led to a diagnosis of combined ocular and cerebral toxoplasmosis. After 6 weeks of antiparasitic therapy, her retinal lesions became inactive and her cerebral lesions improved. Immunosuppressed patients with necrotizing retinochoroiditis should be suspected of having toxoplasmosis. Accurate differentiation between this condition and CMV, and early intervention with the appropriate treatment may be critical to preserve the best vision.