Clinical, Serological, and Genetic Characteristics of a Hungarian Myositis-Scleroderma Overlap Cohort

Abstract

Overlap myositis is a distinct subgroup of idiopathic inflammatory myositis (IIM) with various clinical phenotypes. The aim of this study was to determine the clinical, serological, and genetic features of systemic sclerosis (SSc)-IIM overlap patients. It was a retrospective study using clinical database of 39 patients, fulfilling both the criteria of SSc and IIM. 56.4% of the patients had limited cutaneous, 43.6% had diffuse cutaneous SSc, whereas 7.7% of the patients had dermatomyositis and 92.3% polymyositis. The two diseases occurred simultaneously in 58.97%, while 10.26% in myositis and 30.77% in scleroderma were initially diagnosed. The frequencies of organ involvement were interstitial lung disease 71.8%, dysphagia 66.7%, cardiac involvement 41%, pulmonary arterial hypertension (PAH) 30.8%, and renal involvement 12.8%, respectively. The presence of human leukocyte antigen $\left(\text{HLA}\right)-\text{DRB}1\ast 03$ and $\text{DQA}1\ast 051\ast 01$ alleles were significantly higher in the overlap patients than in healthy controls (82.35% vs. 27.54%; $p<0.0001$ and 88.24% vs. 30.16; $p<0.0001$ ). Certain clinical parameters, such as fever at diagnosis (41.67% vs. 7.41%, $p=0.0046$ ), cardiac involvement (83.33% vs. 22.22%, $p=0.0008$ ), subcutaneous calcinosis (41.66 vs. 11.11, $p=0.01146$ ), and claw hand deformity (25% vs. 11.11%, $p=0.00016$ ) were significantly associated with the presence of PAH. Upon comparison, the overlap patients and anti-Jo-1 positive antisynthetase patients showed similarities in terms of genetic results and major clinical features; however, SSc-IIM overlap patients could be distinguished with higher erythrocyte sedimentation rate (ESR) level, more frequent presence of Raynaud’s phenomenon ( $p<0.0001$ ; OR: 20.00), dysphagia ( $p<0.0001$ ; OR: 15.63), and infrequent livedo reticularis ( $p<0.01$ ; OR: 0.11). SSc-IIM overlap myositis is a unique group within IIM-s possessing characteristic clinical features.