Limbic encephalitis - small cell lung cancer

Case contributed by Dr Andrew Dixon

Presentation

Seizures and memory loss.

Patient Data

Age: 70
Gender: Male

MRI Brain

Modality: MRI

Subtle abnormal high T2 and DWI signal within the left mesial temporal lobe.

PET Scan (FDG)

Modality: Nuclear medicine

Markedly FDG avid abnormality within the left mesial temporal lobe corresponding to the MRI abnormality. An additional FDG avid focus is seen at the right lung hilum. 

CT Chest

Modality: CT

CT shows a right hilar / trachoebronchial soft-tissue mass corresponding to the FDG avid tissue on PET scan. 

Case Discussion

The differential diagnosis for abnormal mesial temporal signal without enhancement on MRI is broad and includes infarction, HSV encephalitis, status epilepticus, low grade astrocytoma, gliomatosis cerebri and limbic encephalitis

The marked FDG avidity on PET scan and right hilar mass however strongly favour the diagnosis of paraneoplastic limbic encephalitis. Small cell lung cancer (as was diagnosed in this case on transbronchial biopsy) is the classic cause of limbic encephalitis however many other tumours can also cause the phenomenon. 

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Case Information

rID: 21604
Case created: 3rd Feb 2013
Last edited: 4th Oct 2016
Inclusion in quiz mode: Included

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