[Clinical and myopathological features of Jo-1 syndrome]

To report the clinical and myopathological features of 16 patients with Jo-1 syndrome.

Sixteen patients were recruited in this study, who were diagnosed as Jo-1 syndrome in Department of Neurology of Peking University First Hospital from January, 2011 to July, 2015. The clinical data and myopathological data were analyzed.

The mean onset age was 41±14 (21-68) years old. 87.5% was female. The median duration was 9.5 months (1-192 months). The main clinical manifestations were weakness in 13 cases (81.2%), arthritis in 10 cases (62.5%), interstitial lung diseases in 8 cases (50%), dermatomyositis-like skin lesions in 5 cases (31.2%), fever in 3 cases (18.8%), Raynaud's phenomenon in 2 cases (12.5%) and mechanic's hands in 2 cases (12.5%). There were 3 cases with other connective tissue diseases and 1 case with non-Hodgkin's lymphoma. Mean serum CK was 3 054±2 058(470-5 222) U/L. All patients had anti-Jo-1antibody, combined with anti- Mi-2 antibody in 1 case, anti-Ro-52 antibody in 5 cases, and anti-nuclear antibody in 5 cases. 4/5 cases showed myopathic changes for electromyography (EMG) tests. Myopathological changes included edema, fragmentation and inflammatory infiltration in perimysium in 14 cases (87.5%), muscle atrophy in 13 cases including 7 cases(43.8%) predominantly in perifascicular field. Muscle fiber necrosis appeared in 8 cases with predominantly in perifascicular area in 4 cases (25%). Muscle fiber regeneration occurred in 11 cases with predominantly in perifascicular field in 5 cases (31.2%). CD8 positive T-lymphocytes, CD20 positive B-lymphocytes and CD68 positive macrophages infiltrated in various degrees, most of which were located in perimysium. MHC-Ⅰ were expressed on muscle fiber membranes in different degrees, including 7 cases (43.8%) predominantly in the cytoplasm of perifascicular muscle fibers. C5b-9 deposited in perifascicular muscle fiber membranes in 7 cases (43.8%) and perifascicular capillaries in 2 cases (12.5%).

The main manifestations of this group of Jo-1 syndrome are weakness, arthritis and interstitial lung diseases, and dermatomyositis-like skin lesions, fever, Raynaud's phenomenon, and mechanic's hands can also be seen. Edema, fragmentation and inflammatory infiltration in perimysium are common. Pathological changes in perifascicular fields appear in some cases.