Sudden onset weakness in an immunocompromised patient

Abstract

Toxoplasmosis is an infection caused by the intracellular parasite Toxoplasma gondii. Human infection usually occurs via an oral or transplacental route. In adults, most infections are subclinical, but severe infection can occur in patients who are immunocompromised, particularly those with AIDS or a history of transplantation. In our patient, a steroid-induced immunosuppression was likely to blame for her susceptibility to the pathogen. Imaging with a non-contrast CT scan often depicts an isodense lesion with surrounding edema and mass effect. On MRI, T2-weighted FLAIR images reveal a hyperintense signal consistent with the underlying mass and edema. On T1-weighted MRI the lesion is often hypo/isodense to gray matter with ring enhancement following the administration of contrast. Diffusion-weighted images often show restricted diffusion (Fig. 1). Histology demonstrated an area of necrosis with scattered cysts (arrow) containing basophilic bradyzoites consistent with toxoplasma micro-organisms (Fig. 2). In our patient, a mild perivascular lymphoplasmacytic infiltrate with scattered cells positive for Epstein-Barr virus (EBV) was present raising the possibility of an early EBV-associated lymphoproliferative disorder. The primary treatment consists of a regimen of pyrimethamine and sulfadiazine.