Descriptive analysis of a single center series of 23 patients with positive PM-Scl antibody

Background: PM-Scl antibodies (abs) belong to the group of myositis-associated antibodies and typically determine a nucleolar or speckled pattern on immunofluorescence. These abs found in patients (pts) with Scleromyositis and, less frequently, in isolated forms of Systemic sclerosis (SSc), Polymyositis (PM) and Dermatomyositis (DM). In SSc pts PM-Scl +, pulmonary involvement seems less severe, while they show more frequent arthritis. Raynaud's phenomenon (RP), digital ulcers (DU) and gastroesophageal involvement appear to be less frequently expressed. In myositis the association with esophageal and lung involvement is well known. Objectives: To characterize demographic and clinical features of a single center series of PM-Scl positive patients. Methods: Sera from 48 SSc and 60 idiopathic inflammatory myophaties (MII) attending local outpatient clinic, detected with EUROIMMUNE Myositis Profile 4 kit, were tested to search PM-ScL antibodies. Demographic, laboratory and clinical data (RP, arthritis, DU, muscular involvement, disphagia) were retrospectively retrieved from available clinical charts. The presence of interstitial lung disease (ILD), was evaluated by HRCT (measured by using score of Goh for the extension) and functional respiratory testing (FVC and DLCO). Severe ILD was defined by: Goh score of>20 and FVC and DLCO <75%. Results: 23 Pts (18 F) resulted positive for PM-Scl. The mean age was 60.5±9.4 years and the mean disease duration was 145.9± 76.3 months. 1 patient had negative ANA, 1 showed ANA anticentromere and 1 dot pattern; the remaining 20 patients (86,9%) were ANA+ showing nucleolar pattern. By applying available formal classification criteria 5 (21.7%) pts were diagnosed as DM, 2 (8.7%) as DM amyopathic, 3 (13.05%) as overlap Scleromyositis, 3 (13.05%) as PM, 1 (4.4%) as cancer associated PM, 9 (39.1%) as SSc (2 diffuse, limited 6, intermediate 1). 13 (56.5%) pts had no evidence of cytopathic muscle involvement (defined as normal CPK, myoglobin and LDH). 5 pts (21.7%) presented a Goh score >20, 1 FVC <75%, and 7 (30.4%) DLCO <75%. 4 pts presented arthritis. 14 (60.8%) had RP, 6 (26%) DU, 8 (34.8%), dysphagia (see images 1). When compared with patients with SSc and MII negative for PM-Scl, MII PM-Scl + pts did not show significant greater risk of developing ILD (Goh>20)dysphagia or minor muscle involvement. SSc PM-Scl + pts seem to have a greater risk of developing arthritis and DU than their corresponding SSc PM-Scl negative pts (p<0.05) while no differences did emerged about ILD (Goh>20) and dysphagia. Conclusions: The role of PM-Scl as a risk factor for ILD in MII pts is not confirmed, but should be considered the positivity in the control group of Jo1, representing per se a major risk factor for this complication (image 2). For patients with SSc is confirmed the role of PM-Scl as a risk factor for arthritis and digital ulcers but not for ILD. References: Long-term out come of patients with polymiositis/dermatomyositis and anti PM/Scl antibody. Marie et al. Journal of Dermatology 2010; 162(2): 337–44