A case of primary Sjögren's syndrome complicated with inflammatory myopathy and interstitial lung disease

We experienced a case of a 63-year-old woman with primary Sjögren's syndrome (pSS) complicated with inflammatory myopathy and interstitial lung disease (ILD). She had suffered from morning stiffness and dry mouth for 1 year without being medically examined. A chest CT scan demonstrated ground glass opacity and a reticular shadow in the lower lung field. A diagnosis of SS was made based on positive findings from Schirmer's test, sialography of the parotid gland, a labial salivary gland biopsy and the presence of anti-SS-A antibody. Musculoskeletal symptoms were absent; however, the elevation of creatine kinase (CK) as well as magnetic resonance imaging (MRI)-proven inflammatory change of bilateral muscles of the thigh was evident. Histological examination of the thigh revealed diameter variation, degeneration of muscle fibers and inflammatory cell infiltration in the perivascular area, corresponding to the inflammatory myopathy of pSS. Oral prednisolone 30 mg/day was introduced, and serum CK rapidly decreased within 2 weeks. ILD also responded well to prednisolone without relapse. These clinical outcomes are consistent with extraglandular organ involvement of pSS.