Limbic encephalitis

Case contributed by Melbourne Uni Radiology Masters
Diagnosis certain


Rapid onset dementia in a young man. Complex neuropsychiatric presentation evolving over three years with severe narcolepsy, ataxia, supranuclear gaze palsy, craving sweet foods, abnormal movements (choreiform movements, ?myoclonus), gait abnormalities, psychosis and cognitive impairment. Rapidly progressing over last two months.

Patient Data

Age: 39-year-old
Gender: Male

MRI Brain (selected series)


Right temporo-insular T2 hyperintensity.

This is associated with gyral and possibly leptomeningeal enhancement in the anterior temporal pole and anterior insula.

No associated diffusion restriction or convincing CBV increase (not shown). Spectroscopy shows moderate choline elevation (not shown).

Left hippocampal formation demonstrates subtle FLAIR hyperintensity, raising the possibility of contralateral involvement.

Remainder of the brain is normal.

No region of diffusion restriction to suggest acute infarct.

Incidental right maxillary sinus mucous retention cyst.

Conclusion: Imaging differential diagnosis has not significantly changed. Limbic-encephalitis is favored over herpes simplex encephalitis on clinical grounds.

Although still an imaging possibility, the pattern of enhancement is not classic for glioma.

Case Discussion

The brain lesion has been also biopsied: 

MICROSCOPIC DESCRIPTION: Paraffin sections show fragments of cerebral cortex and white matter. These show perivascular accumulation of small lymphoid cells around small caliber blood vessels, predominantly in white matter, but also focally within cortex. Lymphoid cells are CD4>CD8 T lymphocytes with smaller numbers of CD20+ B lymphocytes and CD68+ monocyte-macrophages. There is widespread microglial activation and astrocytic gliosis. No atypical lymphoid cells are identified. There are no granulomas and no evidence of demyelination is seen. There is no evidence of tumor. Immunostaining for IDH-1 R132H is negative. Cortical lamination is preserved. There is no polioclasis and no microglial nodules or viral inclusion bodies are seen. There is no spongiform change. Immunostaining for A-beta protein is negative. No plaques or neurofibrillary tangles are identified and there are no ubiquitin glial inclusions. Moderate numbers of neurons are noted in white matter.

DIAGNOSIS: Brain biopsies: T lymphocytic angiotropic inflammatory changes consistent with cerebral angiitis, viral encephalitis or auto-immune encephalitis.

This patient was later diagnosed with a primary testicular cancer.

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