Lambert–Eaton myasthenic syndrome (LEMS) is a rare paraneoplastic neurological syndrome of the neuromuscular transmission. The symptoms often progress slowly and can be misdiagnosed in early stage. Seropositive SOX‐1 antibodies are support for the diagnosis of LEMS and have high specificity for small cell lung cancer (SCLC). In this paper, we report a case of a 56‐year‐old man with smoking history who was admitted to hospital with progressive muscle weakness of the proximal legs. LEMS was diagnosed by repetitive nerve stimulation (RNS) testing and seropositive SOX‐1 antibodies. Primary screening with chest computed tomography (CT) and integrated PET/CT did not reveal any tumor. After continuous follow‐up, SCLC was found by chest CT and confirmed with pathological examination 10 months after the diagnosis of LEMS. Long‐term follow‐up and screening for occult SCLC in LEMS patients with positive SOX‐1 antibodies are very important.

中文翻译：

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SOX-1 抗体阳性兰伯特-伊顿肌无力综合征伴隐匿性小细胞肺癌：一例报告

兰伯特-伊顿肌无力综合征（LEMS）是一种罕见的神经肌肉传导性副肿瘤性神经综合征。症状往往进展缓慢，早期可能被误诊。血清阳性 SOX-1 抗体支持 LEMS 的诊断，并且对小细胞肺癌 (SCLC) 具有高度特异性。在本文中，我们报道了一名有吸烟史的 56 岁男性病例，他因进行性腿部近端肌肉无力而入院。 LEMS 通过重复神经刺激 (RNS) 测试和血清 SOX-1 抗体呈阳性来诊断。胸部计算机断层扫描 (CT) 和综合 PET/CT 初步筛查未发现任何肿瘤。经过持续随访，确诊LEMS后10个月，胸部CT发现SCLC，并经病理检查确诊。对 SOX-1 抗体阳性的 LEMS 患者进行长期随访和筛查隐匿性 SCLC 非常重要。