Texas Tech University Health Sciences Center El Paso, USA.
J Investig Med High Impact Case Rep. 2022 Jan-Dec;10:23247096221121403. doi: 10.1177/23247096221121403.
Dermatomyositis sine dermatitis (DMSD) is one of the rare idiopathic inflammatory myopathies. Based on predominant symptoms faced by patients, it is classified into 3 types: (1) classic dermatomyositis (DM), where patients have both muscle and skin symptoms; and (2) amyopathic DM, when only skin symptoms present with no muscle involvement. Whereas (3) DMSD has mainly muscle symptoms with muscle antibodies but no skin rashes. There have been only nearly 10 published articles about DMSD proving this disease's scarcity. At the same time, it shows the importance of discussing the unusual presentation of such a rare disease. Here we present, a 28-year-old woman with worsening proximal muscle weakness. The decreased muscle strength on physical examination and elevated creatinine kinase required more work up for autoimmune disease. Interestingly, on muscle biopsy, anti-melanoma differentiation-associated gene 5 (anti-MDA5) antibody returned positive, and the patient responded well to 3 days course of steroids. The lack of skin involvement, the predominance of muscle symptoms, and positive anti-MDA5 antibody indispensably diagnosed patients with DMSD. The previously published articles have proved the association between anti-NXP-2 antibody and DMSD, which was not seen in our case. The systemic involvement of DMSD can lead to interstitial lung disease, where due to diffuse alveolar damage and pulmonary fibrosis, patients end up requiring intubation and may be associated with higher-level mortality. In our case, chest X-rays and computed tomography (CT) scans were unremarkable for lung involvement, so as no paraneoplastic syndromes were present, which has also been reported in DMSD patients previously.
无皮肌炎的皮肌炎（DMSD）是一种罕见的特发性炎症性肌病。根据患者的主要症状，它分为 3 种类型：（1）经典皮肌炎（DM），患者既有肌肉症状又有皮肤症状；（2）无肌病性皮肌炎，当只有皮肤症状而没有肌肉受累时；（3）DMSD 主要有肌肉症状，伴有肌肉抗体，但无皮疹。仅有近 10 篇关于 DMSD 的已发表文章证明了这种疾病的罕见性。同时，这也表明了讨论这种罕见疾病不常见表现的重要性。在这里，我们介绍了一位 28 岁的女性，她的近端肌肉无力逐渐加重。体格检查时肌肉力量下降和肌酸激酶升高需要进一步检查自身免疫性疾病。有趣的是，在肌肉活检中，抗黑色素瘤分化相关基因 5（抗-MDA5）抗体呈阳性，患者对 3 天的类固醇治疗反应良好。缺乏皮肤受累、肌肉症状为主和阳性抗-MDA5 抗体必不可少地诊断了 DMSD 患者。以前的已发表文章已经证明了抗-NXP-2 抗体与 DMSD 之间的关联，但在我们的病例中没有发现。DMSD 的系统性受累可导致间质性肺病，由于弥漫性肺泡损伤和肺纤维化，患者最终需要插管，可能与较高的死亡率有关。在我们的病例中，胸部 X 线和计算机断层扫描（CT）均未显示肺部受累，也没有发现副肿瘤综合征，这在以前的 DMSD 患者中也有报道。
