Cerebral Toxoplasmosis as an Uncommon Complication of Biologic Therapy for Rheumatoid Arthritis: Case Report and Review of the Literature.

Toxoplasmosis is one of the most common opportunistic infections, mainly reported in patients with acquired immunodeficiency syndrome (AIDS). Patients with rheumatoid arthritis (RA) have also been linked to reactivation of toxoplasmosis due to immunosuppressive treatment, although biologic drugs have seldom been implicated. We present a case of cerebral toxoplasmosis in a 62-year-old female patient with RA after initiation of biologic therapy (adalimumab). The patient had detectable serum IgG antibodies to toxoplasma gondii, was also on chronic treatment with other non-biologic drugs and presented with worsening disorientation, unsteady gait and left hemiparesis. Imaging studies showed a space-occupying lesion in the right basal ganglia with ring-enhancement. Brain biopsy confirmed the diagnosis of toxoplasmosis and the patient was treated with pyrimethamine and sulfadiazine for 6 weeks, showing complete recovery on follow-up. A review of the literature yielded other four case reports of cerebral toxoplasmosis implying biologic drugs; however, data concerning toxoplasmosis serologic testing, prophylaxis and treatment in these patients are lacking. Each case must be carefully evaluated prior to treatment and a high-index of suspicion in seropositive patients is warranted. Since the use of biologic drugs is increasing, further research is needed to establish practical guidelines for seropositive patients receiving immunosuppressive treatment.