Toxoplasmic encephalitis of basal ganglia with tumor-like features proven by pathogen-specific polymerase chain reaction and direct DNA sequencing.

We report a case of a young female patient who developed progressive neurological dysfunction with a ring-enhancing tumor-like nodule on brain magnetic resonance imaging. Urgent surgery was performed to remove the mass in the left basal ganglia. Pathological findings showed that the necrotic brain areas were accompanied by congestion, edema, discrete hemorrhage, and intestinal and perivascular lymphohistiocytic infiltration. Immunohistochemical staining results showed that Toxoplasma gondii (T. gondii) immunoreactivity was detected in both cysts and tachyzoites in these areas. The glycerol-3-phosphate dehydrogenase gene (B1) of T. gondii was amplified by sequence-specific polymerase chain reaction (PCR) and the PCR products were bi-directional Sanger sequenced. A 195 bp consensus sequence of the gene B1 was found to be 98% identical to a reference T. gondii sequence (GenBank accession No. kx270373). The final diagnosis was toxoplasmic encephalitis in the left basal ganglia. This report suggests that PCR and bi-directional DNA sequencing of T. gondii gene might be the most convenient and rapid tools for accurate diagnosis of toxoplasmic encephalitis .