[Clinical analysis of paraneoplastic neurological syndrome associated with thymoma]

Objectives: To investigate the clinical features, diagnosis and treatment of antibody mediated paraneoplastic neurological syndrome associated with thymoma. Methods: From 2012 to 2017, the paraneoplastic antibody and neuron antibody were tested from both blood and cerebrospinal fluid (CSF) in consecutive patients clinically suspected with neurological paraneoplastic syndromes/unknown encephalitis in Peking Union Medical College Hospital.The clinical data, lab results, electrophysiological examinations, imaging features, treatment and clinical prognosis were collected.In this study, the patients who met the diagnostic criteria of both thymoma and neurological paraneoplastic syndrome were retrospectively analyzed.The functional severity was assessed by modified Rankin score(mRS). Results: Six patients (4 female and 2 male) were included for the analysis.Of them, 4 patients presented with limbic encephalitis, 1 with peripheral neuropathy accompanying with myasthenia gravis and 1 with spinal and cerebella degeneration.Three patients were in severe condition (mRS=5). Positive α-amino-3-hydroxy-5-methyl-4-iso xazolepropionic acid receptor, antibody (AMPAR) was identified in 3 patients(2 in blood and CSF, 1 in blood), CV2 plus acetylcholine receptor antibody (ACH-Ab) positive in blood was seen in 1 patient and positive N-methyl-D-aspartate receptor (NMDAR) in blood and CSF in 1 patient. Brain MRI showed abnormalities in 2 patients.The CT scan revealed thymoma in all 6 patients.All patients received intravenous immunogloblin (IVIG) and/or glucocorticoid immediately after diagnosis.Furthermore, thymectomy was performed in 5 patients. All the patients were remarkably improved with mRS 0-1 at discharge.Five patients were clinical stable within follow-up of 1-2.5 years.However, one patient who refused thymectomy experienced several clinical recurrencs. Conclusions: Antibodies mediated paraneoplastic neurological syndrome/autoimmune encephalitis can occur in patients with thymoma with typical characteristics. The correlated antibody test and chest CT might be important in patients clinically suspected with neurological paraneoplastic syndrome or encephalitis with unknown reason. Surgical thymectomy combining with active immunological treatment may play a role in the favorable prognosis, even in those clinical severe patients.