Abstract Details

Title Atypical MRI Features of Cerebral Toxoplasmosis: Restricted Diffusion and Diagnostic Challenges

Topic Infectious Disease

Presentation(s) P9 - Poster Session 9 (5:00 PM-6:00 PM)

Poster/Presentation
Number 3-012

Objective To describe a case of cerebral toxoplasmosis presenting with diffusion restriction on MRI, an atypical finding that mimics CNS lymphoma or pyogenic abscess.

Background Cerebral toxoplasmosis presents on MRI brain with contrast as ring-enhancing lesions with surrounding edema and no diffusion restriction, distinguishing it from primary CNS lymphoma and pyogenic abscess. However, in atypical cases, diffusion restriction has been reported due to high cellularity or viscous necrotic material. Previously reported cases have demonstrated restricted diffusion within lesion cores, peripheral “eccentric target” signs, and heterogeneous diffusion corresponding to areas of necrosis or high cellularity. Recognizing atypical imaging patterns is critical to avoid misdiagnosis and therapeutic delays.

Design/Methods We report the case of a patient with cerebral toxoplasmosis who underwent clinical evaluation, laboratory testing, and neuroimaging. The diagnosis was confirmed via immunoassay of serum Toxoplasma gondii IgG antibody and supported by improvement on imaging following treatment.

Results A 47-year-old male with hypertension presented with weakness and decreased sensation in the bilateral lower extremities and right upper extremity. Brain MRI with contrast revealed multifocal enhancing lesions in bilateral hemispheres, including a 3.9 cm left parietal lobe lesion with vasogenic edema, left lateral ventricle effacement, and 6 mm subfalcine herniation; these lesions demonstrated prominent diffusion restriction within core tissue. Labs were remarkable for positive HIV screen, CD4 count of 26 cells/UL, and toxoplasma IgG antibody of >400 IU/mL, for which six weeks of sulfamethoxazole-trimethoprim was started. Two weeks post-treatment, repeat MRI brain with contrast revealed decrease in size of the lesions and vasogenic edema.

Conclusions

Cerebral toxoplasmosis can rarely demonstrate diffusion restriction on MRI; a feature more commonly associated with CNS lymphoma and pyogenic abscess. This atypical imaging pattern is underrecognized, with few cases previously described. Our case underscores the need to consider toxoplasmosis even when diffusion restriction is present, particularly in immunocompromised patients.

Authors/Disclosures
Hanna Malik, DO PRESENTER	Hanna Malik, DO has nothing to disclose.
Junaid M. Essa, DO	Dr. Essa has nothing to disclose.
Lintu Ramachandran (Baylor College of Medicine)	Lintu Ramachandran has nothing to disclose.

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