Paraneoplastic neurological syndromes with onconeural antibodies: A single center retrospective study.

INTRODUCTION: Paraneoplastic neurological syndromes (PNS) are immune-mediated diseases that occur in patients with tumors and can be associated with onconeural antibodies. Our aim was to describe our cohort of patients with PNS. METHODS: Retrospective analysis of a cohort of patients followed in a Portuguese tertiary center, with autoantibodies against intracellular antigens from our PNS panel, between 2012 and 2017. RESULTS: Among the 882 patients with suspected PNS (1029 samples), 37 (4.2%) had positive and 27 (3.1%) weak positive antibodies. A total of 17 (29.3%) PNS were diagnosed, 5 were classic syndromes. Autoantibodies found were anti-Yo, anti-Hu, anti-titin, anti-Ma2, anti-SOX1, anti-Ri and anti-CV2/CRMP5. They were associated with thymoma, breast, colon, parotid gland and lung (small-cell, neuroendocrine or carcinoid) cancer. Among the 17 PNS patients, no tumor was found in 4 (mean follow-up of 46 months); no patients improved with tumor treatment, while 8 improved with immunotherapy; ten patients (59%) died during follow-up. Twenty (60.6%) patients with positive antibodies and 21 (84.0%) with weak positive were not diagnosed with a PNS. CONCLUSIONS: PNS had highly heterogenous clinical presentations. Response to tumor treatment was overall poor, with an unfavorable prognosis. In our cohort, only 29.3% of the patients with positive antibodies were diagnosed with a PNS.