Toxoplasmosis - Diagnosis

Diagnosis

Toxoplasmosis can be difficult to distinguish from primary central nervous system lymphoma, and as a result, the diagnosis is made by a trial of therapy (pyrimethamine, sulfadiazine + leucovorin), followed by a brain biopsy if the drugs produce no effect clinically and no improvement on repeat imaging.

Detection of Toxoplasma gondii in human blood samples may also be achieved by using the polymerase chain reaction (PCR). Inactive cysts may exist in a host which would evade detection.

Toxoplasmosis cannot be detected with immunostaining. Lymph nodes affected by toxoplasma have characteristic changes, including poorly demarcated reactive germinal centers, clusters of monocytoid B cells and scattered epithelioid histiocytes.