[Non-small cell carcinoma presenting as limbic encephalitis. Place of endobronchial ultrasound in the diagnosis]. / Encéphalite limbique paranéoplasique révélant un cancer bronchique non à petites cellules. Place de l'échographie endobronchique dans le diagnostic étiologique.

INTRODUCTION: Limbic encephalitis is a rare neurological paraneoplastic syndrome, characterized by anterograde amnesia, epilepsy and confusion. Diagnosis of the underlying cancer is essential for treatment. CASE REPORT: A 55-year-old heavy smoker was admitted on account of general physical deterioration and neurological symptoms. The diagnosis of limbic encephalitis was based on rapidly progressive symptoms, inflammatory cerebrospinal fluid, increased signal intensity in the temporal lobes on magnetic resonance imaging and the presence of anti-neuronal anti-Ma2 antibodies. The initial work-up, including positron emission tomography, did not reveal any cancer. Four months later, sub-carenal lymphadenopathy was detected. Echo-guided transbronchial and mediastinoscopic biopsies revealed bronchial adenocarcinoma (TxN2M0). Neurological and general physical deterioration followed despite radio-chemotherapy giving total control of the tumour macroscopically. The patient died two months after the end of his treatment as a result of staphylococcal septic shock. CONCLUSIONS: The neurological prognosis is poor. The search for bronchial cancer, when suspected, should include positron emission tomography, to be repeated if necessary, and sampling of the mediastinal lymph nodes using endobronchial ultrasound.