Systemic and Bilateral Severe Ocular Toxoplasmosis Resembling Autoimmune Phenomena: A Case Report

Purpose: To present an atypical case of severe bilateral ocular toxoplasmosis with systemic involvement that initially mimicked an autoimmune etiology, posing challenges to its diagnosis and treatment. Case Report: A 39-year-old immunocompetent male was admitted to the hospital due to a presumed pulmonary thromboembolism concomitant with an abrupt onset of vision loss. Initial differential diagnoses included antiphospholipid syndrome and systemic lupus erythematosus, prompting the administration of corticosteroid pulses and rituximab. Despite observing a partial systemic response, there was no improvement in visual acuity. Subsequent aqueous humor polymerase chain reaction confirmed Toxoplasma gondii infection, leading to the introduction of oral antibiotic therapy. The patient’s condition showed a partially favorable response; however, the treatment could not reverse the permanent retinal damage. Conclusion and importance: This case underscores the importance of ruling out an infectious etiology in all cases of uveitis. Additionally, it alerts clinicians to the possibility that elevated positive autoantibodies may result from a severe inflammatory reaction caused by pathogens rather than an autoimmune or autoinflammatory disease, particularly in instances of poor treatment response or atypical clinical presentation.