SAT0482 Clinical and Serological Features of Patients with Dermatomyositis Complicated by Spontaneous Pneumomediastinum
Authors: Z. Chen, Y. Wang, M. Kuwana, L. Sun
Journal: Annals of the Rheumatic Diseases (2015)

<h3>Background</h3> Interstitial lung disease (ILD) is a common complication and is associated with the prognosis of dermatomyositis (DM). The respiratory function deteriorate quickly and leads to poor prognoses in some individuals, a condition known as rapidly progressive ILD (RP-ILD). Some patients with DM associated RP-ILD present characteristic cutaneous rash of DM but have not clinically significant muscle weakness, a subgroup of DM designated as clinically amyopathic dermatomyositis (CADM) [1]. Recent studies have demonstrated that most patients with DM and RP-ILD are positive for anti-melanoma differentiation-associated gene 5 (MDA5). Spontaneous pneumomediastinum (PNM) is a rare but devastating illness in DM-ILD. Albeit that previous studies have revealed that some patients with DM and PNM have mild muscle involvement and are anti-MDA5 positive [2], the clinical and serological features of this severe entity have not been fully elucidated. <h3>Objectives</h3> To explore the clinical and serological features of patients with DM and PNM. <h3>Methods</h3> A total of 93 (68 classic DM and 25 CADM) patients were recruited. Anti-MDA5 antibodies were detected using ELISA [3]. Variables were compared between patients with and without PNM. Multivariate analysis was performed using a multivariate logistic regression model. The following variables were assessed as potential factors associated with spontaneous PNM in DM: presence of RP-ILD, DM subgroup (classic DM or CADM), presence of skin ulcers and presence of anti-MDA5 antibodies. <h3>Results</h3> A total of 11 patients (7 man and 4 women) developed PNM. Seven patients were diagnosed with CADM while 4 patients were diagnosed with classic DM. Despite being treated with the combination of glucocorticoids and immunosuppressants, during the follow-up period, 6 patients died of respiratory failure, with a varied interval after the occurrence of PNM ranged from 3 to 48 weeks. Compared with DM patients without PNM, DM patients with PNM had significantly higher frequencies of RP-ILD (63.6% vs 24.4%, <i>P</i> =0.01), anti-MDA5 antibodies (90.9% vs 52.4%, <i>P</i> =0.02), CADM diagnoses (63.6% vs 22.0%, <i>P</i> =0.007) and cutaneous ulcers (36.4% vs 10.2%, <i>P</i> =0.04), but significantly lower creatine kinase (CK) levels (58.5 vs 284 ng/ml, <i>P</i> =0.04). The logistic multivariate analysis indicated that cutaneous ulcer was the only independent risk factor for the occurrence of PNM in DM (OR =5.98, 95% CI 1.12–31.98, <i>P</i>=0.037). <h3>Conclusions</h3> Spontaneous PNM is a refractory complication and tends to occur in DM patients with RP-ILD, anti-MDA5 antibody, CADM diagnosis and low CK level, especially in patients with cutaneous ulcers. <h3>References</h3> Sato S, Kuwana M (2010) Clinically amyopathic dermatomyositis. Curr Opin Rheumatol 22:639-643. doi:10.1097/BOR.0b013e32833f1987 Le Goff B, Cherin P, Cantagrel A, Gayraud M, Hachulla E, Laborde F, Papo T, Sibilia J, Zabraniecki L, Ravaud P, Puechal X (2009) Pneumomediastinum in interstitial lung disease associated with dermatomyositis and polymyositis. Arthritis Rheum 61 (1):108-118. doi:10.1002/art.24372 Sato S, Hoshino K, Satoh T, Fujita T, Kawakami Y, Fujita T, Kuwana M (2009) RNA helicase encoded by melanoma differentiation-associated gene 5 is a major autoantigen in patients with clinically amyopathic dermatomyositis: Association with rapidly progressive ILD. Arthritis Rheum 60:2193-2200. doi:10.1002/art.24621 <h3>Disclosure of Interest</h3> None declared