CASE REPORT   

Il Giornale Italiano di Radiologia Medica 2019 Marzo-Aprile;6(2):119-27

DOI: 10.23736/S2283-8376.19.00181-5

Copyright © 2019 EDIZIONI MINERVA MEDICA

language: English, Italian

Paraneoplastic limbic encephalitis: a challenging diagnosis

Silvia STORER ✉, Annalisa MONE, Marco BARILLARI, Giancarlo MANSUETO

Institute of Radiology, G.B. Rossi Hospital, University of Verona, Verona, Italy

Paraneoplastic limbic encephalitis is a rare neurological disorder characterized by subacute onset, in day or up to twelve weeks, of seizures, short-term memory loss, confusion and psychiatric symptoms suggesting involvement of the limbic system. It is produced by an autoimmune T-cell response caused by onconeuronal antibodies against neuronal, cell-surface or synaptic antigens. The tumors most commonly associated with paraneoplastic autoimmune encephalitis are small cell lung cancer, testicular cancer, ovarian teratoma and thymoma. Neurological symptoms can precede the cancer diagnosis, influencing clinical work-up. A 78-year-old man presented to the emergency department with subacute onset of confusion, short-term memory impairment and seizures. Brain computed tomography (CT) is negative for acute cerebrovascular events and brain magnetic resonance imaging (MRI) shows T2/fluid attenuated inversion recovery hyperintensity affecting mesial temporal lobes and hippocampi. A lumbar puncture is performed, cerebrospinal fluid analysis reveals normal cell count and biochemistry, and lack of microbiological findings. An immunological test demonstrates anti-Hu antibodies positivity. In the strong suspicion of autoimmune paraneoplastic encephalitis, 18-FDG positron emission tomography-CT shows a hypermetabolic focus in the upper lobe of the right lung with lower homolateral paratracheal lymphadenopathy. These findings are confirmed by chest CT scan, with histologically proven small cell lung cancer. Even if autoimmune encephalitis remains a diagnosis of exclusion with more common disorders (infectious or metabolic causes), brain MRI plays a key role in the management of patients with subacute onset of altered mental status, suggesting autoimmune encephalitis. Therefore, the detection of onconeural antibodies and an underlying tumor associated can ensure an effective treatment regimen with a better outcome.

KEY WORDS: Paraneoplastic syndromes; Encephalitis; Magnetic resonance imaging; Autoantibodies