A 35-year-old man was diagnosed with psoriatic arthritis treated with methotrexate and cyclosporine, the latter was then interrupted. Subsequently, etanercept was introduced, administered for 10 years and then replaced with ustekinumab. Six months after treatment with ustekinumab, patient underwent a chest CT scan for pneumonia, showing an anterior mediastinal mass which turned out to be a thymoma. He was referred to our department with fatigue, difficulty in raising arms and transient episodes of diplopia after exertion. Clinical history revealed that these symptoms had begun about 7 years previously but were ascribed to psoriatic arthritis. A diagnosis of anti-acetylcholine receptor antibodies positive myasthenia gravis was made; a higher dosage of methotrexate and prednisone were started with regression of symptoms. Our case increases the number of clinical reports of myasthenia gravis onset in patients with a history of rheumatic disease treated with anti-TNFα drugs. We speculate that ustekinumab could contribute to clinical worsening.

中文翻译：

---

依那西普和优特克单抗治疗银屑病关节炎后重症肌无力：病例报告

一名 35 岁男子被诊断患有银屑病关节炎，接受甲氨蝶呤和环孢素治疗，后者随后被中断。随后，依那西普被引入，给药 10 年，然后被优特克单抗取代。使用优特克单抗治疗六个月后，患者接受了肺炎的胸部 CT 扫描，显示前纵隔肿块，结果证明是胸腺瘤。他因疲劳、举臂困难和劳累后短暂的复视被转诊到我们科。临床病史显示，这些症状大约在 7 年前开始出现，但归因于银屑病关节炎。诊断为抗乙酰胆碱受体抗体阳性重症肌无力；随着症状的消退，开始使用更高剂量的甲氨蝶呤和泼尼松。我们的病例增加了有风湿病病史且接受抗 TNFα 药物治疗的患者出现重症肌无力的临床报告数量。我们推测优特克单抗可能导致临床恶化。