A group of patients with anti-aminoacyl tRNA synthetase (ARS) antibody, or anti-synthetase syndrome (ASS), may constitute a unique subtype of dermatomyositis. We compared the cutaneous, muscular and pulmonary manifestations between the ASS and non-ASS groups of dermatomyositis. We analyzed 59 patients with dermatomyositis referred to our university hospital from 2008 to 2016. The patients were examined for skin lesions, routine blood tests, autoantibody profiles using ELISA kits, skin biopsy, and radiological imaging of the lung and muscle diseases. The ELISA kit for measurement of anti-ARS antibodies is prepared to detect antibodies to Jo-1, PL-7, PL-12, EJ, and KS. We also examined antibodies to TIF1-γ, MDA5 and Mi-2. Of 59 patients with dermatomyositis, 20 patients were classified into the ASS group, and the remaining 39 patients were of the non-ASS. Patients with ASS more frequently presented with mechanic’s hands (p=0.012), and systemic symptoms such as fever (p=0.019) and arthralgia (p=0.0037), associated with elevated serum levels of C-reactive protein (p=0.0029). Nineteen of 20 (95%) patients with ASS had interstitial lung disease (ILD) with fibrotic non-specific interstitial pneumonia (fNSIP) or organizing pneumonia/eosinophilic pneumonia (OP/EP) pattern by computed tomographic imaging. Blood chemistry tests revealed significantly higher serum levels of aldolase (ALD) in the ASS group (p=0.0022), although no clear difference in the serum levels of creatinine phosphokinase (CK). As for magnetic resonance imaging of myopathy, patients with ASS showed the presence of fasciitis as well as myositis more frequently (p=0.0041). Patients with ASS are characterized by the higher incidence of mechanic’s hands, systemic inflammation, ILD, and inflammatory myopathy associated with fasciitis, and elevated serum levels of ALD.

Distinct clinicopathologic and radiological manifestations of the skin,  lung,  and muscle diseases in patients with dermatomyositis positive for anti-aminoacyl tRNA synthetase antibodies.