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Metastatic Malignant Lymphoma Mimicking Cerebral Toxoplasmosis with the "Target Sign"
Hiroki Ueno1, Kazumi Norose2, Teppei Kamimura1
1Department of Clinical Neuroscience and Therapeutics, Graduate School of Biomedical and Health Sciences, Hiroshima University, Japan.
Abstract:
We herein report the case of a 60-year-old man with a "target sign" in the left frontal lobe on magnetic resonance imaging (MRI), which is thought to be a specific sign of cerebral toxoplasmosis. 18F-fluorodeoxyglucose-positron emission tomography showed no increased uptake, and 201Tl-single photon emission computed tomography showed the focal uptake in the left frontal lesion. On a brain biopsy, the patient was given a definitive diagnosis of brain metastasis from diffuse large B-cell lymphoma, and cerebral toxoplasmosis was excluded. In the present case, multilayer intensities on MRI may reflect the fast-growing nature of this tumor.
Insights
A brain MRI showed a "target sign," typically indicating cerebral toxoplasmosis. However, further tests and biopsy revealed brain metastasis from diffuse large B-cell lymphoma, not toxoplasmosis.
Area of Science:
- Neurology
- Radiology
- Oncology
Background:
- The
- target sign
Observation:
- A 60-year-old man presented with a
- target sign
Findings:
- 18F-fluorodeoxyglucose-positron emission tomography (FDG-PET) showed no increased uptake.
- 201Tl-single photon emission computed tomography (SPECT) demonstrated focal uptake in the left frontal lesion.
- Brain biopsy confirmed metastasis from diffuse large B-cell lymphoma, excluding cerebral toxoplasmosis.
Implications:
- Multilayer intensities on MRI may indicate a fast-growing tumor.
- This case highlights the importance of comprehensive diagnostic evaluation beyond imaging signs.
- Differentiating brain metastasis from infectious lesions is crucial for appropriate treatment.