OCULAR TOXOPLASMOSIS MISDIAGNOSED AS CYTOMEGALOVIRUS RETINOPATHY IN IMMUNOCOMPROMISED PATIENTS

Background: Cytomegalovirus (CMV) and Toxoplasma gondii both cause nec rotizing retinopathy in immunosuppressed hosts. Because of the high pr evalence of serum antibodies to these agents in the general population and the risks associated with retinal biopsies, diagnosis of these in fections is usually based on clinical findings alone, but the two infe ctions can be confused with one another because of similar clinical fe atures. Accurate diagnosis is critical, however, because both diseases are treatable but require different medical therapies. Methods: Case histories were reviewed for five immunosuppressed patients with necrot izing retinopathy, which was initially diagnosed incorrectly as CMV re tinopathy but was subsequently found to be toxoplasmic retinochoroidit is. Correct diagnosis was based on retinal biopsy (2 cases) or rapid r esponse to antiparasitic drug therapy (3 cases). Factors were sought t hat might help differentiate toxoplasmic retinochoroiditis from CMV re tinopathy at presentation. Results: In all cases, the character of ret inal opacification (densely opaque, thick) and the appearance of lesio n borders (smooth, nongranular) was different from that typically seen with CMV retinopathy. These cases also were characterized by prominen t anterior chamber and vitreous inflammatory reactions (four of five c ases) and relative lack of retinal hemorrhage. One patient subsequentl y developed CMV retinopathy; characteristics of the two lesions in the same eye highlighted the differences between these two infections. Co nclusion: Clinicians should consider ocular toxoplasmosis as a cause o f necrotizing retinopathy in immunosuppressed patients and consider an empiric course of antiparasitic therapy for lesions with features des cribed in this report.