Presentation
Fever and altered mental status for 5 days with underlying immunosuppressive illness and stem cell transplant.
Patient Data
Ill-defined hypodense lesions at the right temporal lobe, left inferior frontal lobe, right frontal lobe and left lentiform nucleus. Some of these lesions are associated with vasogenic edema.
Post-contrast administration, faint enhancement at the left lentiform nucleus lesion.
Multiple intraparenchymal lesions with iso-to-hypointense on T1WI and hyperintense signals on T2WI/FLAIR, in bilateral basal ganglia, bilateral centrum semiovale, bilateral frontal, bilateral temporal, right parietal and right occipital lobes. These lesions demonstrate faint nodular or ring enhancement.
No hydrocephalus. No abnormal leptomeningeal or pachymeningeal enhancement.
Lumbar puncture showed CSF polymerase chain reaction (PCR) Toxoplasma gondii.
The patient was treated with a combination of antibiotics clindamycin and pyrimethamine.
Reassess with MRI brain 3 weeks post-treatment to assess the efficacy of the antibiotics in view of the high mortality rate of CNS toxoplasmosis for this group of patients (retroviral disease and stem cell transplant).
The previously noted multiple intraparenchymal lesions are increasing in size and are more conspicuous in the current study.
Multiple new intra-axial lesions of varying lesions. The old and new lesions are distributed throughout the brain, including bilateral cerebral hemispheres, bilateral cerebellum and brainstem. These lesions are iso-to-hypointense on T1WI and hyperintense on T2WI/FLAIR sequences.
The locations of these lesions include the corticomedullary junction, subcortical regions, deep white matter, bilateral thalami, bilateral basal ganglia, right superior cerebellar peduncle, and brainstem(right-sided medulla oblongata).
Some gyriform-like hyperintensities on T1WI were noted at the right temporal lobe, right occipital lobe, left parietal lobe, bilateral frontal lobes and bilateral lentiform nuclei. These can represent calcification or proteinaceous materials.
Similar restricted diffusion at the right temporal lobe with corresponding blooming artefacts on GRE may represent calcification.
Some of these intraparenchymal lesions show ring enhancement (left thalamus, right frontal lobe, both lentiform nuclei, right temporal lobe and left parietal lobe).
Case Discussion
In the case of cerebral toxoplasmosis, MRI brain is the better imaging modality for accurate assessment of the lesion compared to the CT scan, where the majority of lesions are not conspicuous in CT scan.
For this case, the patient who is immunocompromised (both retroviral disease and stem cell transplant for lymphoma), the close monitoring of cerebral toxoplasmosis with neuroimaging MRI scan (two to three weeks after commencement of treatment) is important to assess the efficacy of the treatment regime, because the mortality rate for this group of patient is very high.
After 3-week of treatment with this regime, the repeated MRI brain showed a poor response to the treatment as progressively increasing numbers and sizes of intracranial brain lesions. Treatment regime was changed after the MRI scan and the patient is awaiting further followup imaging.
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