A RARE CASE OF ANTI MI-2 POSITIVE AMYOPATHIC DERMATOMYOSITIS PRESENTING WITH NSIP

Abstract

SESSION TITLE: Diffuse Lung Disease 1 SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: 10/09/2018 01:15 pm - 02:15 pm INTRODUCTION: Nonspecific interstitial pneumonia (NSIP)-like pattern in Interstitial Lung Disease (ILD) is commonly found in patients with idiopathic inflammatory myopathies (IIM). The type of the IIM and the presence of certain antibodies provide diagnostic and prognostic value. Dermatomyositis (DM) and Amyopathic Dermatomyositis (ADM) with ILD appear to have poorer prognosis in contrast with Polymyositis (PM) with ILD. On the contrary DM with presence of Anti-Mi-2 autoantibodies, which is rarely encountered, tend to have more favorable outcome and lack of significant lung involvement. We present a case of a woman with ADM, positive Anti Mi-2 and NSIP-like ILD. CASE PRESENTATION: 36 F presented with a year history of exertional dyspnea, dry cough and chronic fatigue. PE was remarkable for diffuse bilateral crackles, macular eruption over lateral aspect of arms and Gottron‘s papules. Chest CT showed bilateral ground glass opacities with linear reticulonodular opacities and bronchiectasis. Labs showed CRP of 14.9 mg/L, ANA 1:1280, CK 319, Aldolase 12.TBBx showed chronic interstitial inflammation and interstitial fibrosis. VATS with RUL and RLL wedge biopsies showed findings consistent with NSIP. PFT were suggestive of restrictive pattern. Muscle biopsy results showed few rare atrophic, regenerating fibers and one area of focal perimyosial inflammation. She had positive Anti Mi-2 antibodies. DISCUSSION: Patients that present with characteristic DM rash with minimal or absent muscle involvement are referred as amyopathic dermatomyositis (ADM).Lung involvement is uncommon in ADM. NSIP is the most common pattern in patients with ILD/ADM preceding the onset of cutaneous or muscular manifestations.The antibodies encountered in inflammatory myopathy anticipate prognosis and correlate with clinical manifestations. Autoantibodies are found in ∼50% and are divided into myositis-associated autoantibodies (MAA) and myositis-specific autoantibodies (MSA).Multiple MSA have been described and mainly divided into antisynthetase autoantibodies and non-antisynthetase autoantibodies. Anti Mi-2, which was positive in our patient, is a non-antisynthetase MSA directed against the DNA helicase, is found in <10%. Anti Mi-2 positive tend to be treatment-responsive and present with ADM-type of picture (rash and mild to absent muscle symptoms,) which was our case.Steroids and immunosuppressive agents play an important role in treatment. CONCLUSIONS: NSIP is the most common histological pattern of ILD in inflammatory myopathy including ADMAnti Mi-2 has shown to have a better response to medical management than other DM-ILD. Different antibodies that may be involved in ADM-ILD may play a role in outcomes reported, in terms of prognosis. Presence of Anti Mi-2 antibodies correlated with favorable response to treatment even with significant ADM-ILD. To our knowledge there is no evidence of Anti-Mi2 ADM presenting with ILD. Reference #1: Douglas WW1, Tazelaar HD, Hartman TE, Hartman RP, Decker PA, Schroeder DR, Ryu JH. Polymyositis-dermatomyositis-associated interstitial lung disease.Am J Respir Crit Care Med. 2001 Oct 1;164(7):1182-5. Reference #2: Solomon J, Swigris JJ, Brown KK. Myositis-related interstitial lung disease and antisynthetase syndrome. Jornal brasileiro de pneumologia : publicacao oficial da Sociedade Brasileira de Pneumologia e Tisilogia. 2011;37(1):100-109. Reference #3: Mukae, Hiroshi et al. Clinical Differences Between Interstitial Lung Disease Associated with Clinically Amyopathic Dermatomyositis and Classic Dermatomyositis. CHEST , Volume 136 , Issue 5 , 1341 - 1347 DISCLOSURES: No relevant relationships by Adriana Abrudescu, source=Web Response No relevant relationships by Jonathan Arnedo, source=Web Response No relevant relationships by Yesika Garcia, source=Web Response No relevant relationships by Theo Trandafirescu, source=Web Response