[A case of Sjögren's syndrome complicated by polymyositis and sarcoidosis with HLA-B7 and DR 8: common causes of susceptibility for these diseases].

We describe a case of a Japanese patient initially presenting with Sjögren's syndrome who later developed polymyositis and sarcoidosis. A 67-year-old woman with a 4 month history of myalgia was admitted in April 1998 for examination. The patient had a 10 year history of symptoms consistent with Sjögren's syndrome. A diagnosis of polymyositis was made based on a biopsy of the muscle and an electromyogram. Positive Shirmer and Rose Bengal tests and results of a minor salivary gland biopsy were all consistent with Sjögren's syndrome. Chest computed tomography detected a bilateral hilar lymphadenopathy. Microscopic examination of a mediastinal lymph node demonstrated multiple noncaseating granulomas with multiple epithelioid cells and Langhans-like giant cells. A diagnosis of sarcoidosis was made based on these findings. Hepatitis C infection was also detected by elevated antibody levels. The patient was given 40 mg/day of oral prednisolone and a remission of her myositis and lymphadenopathy was obtained. The patient exhibited HLA-B7 and HLA-DR 8. HLA-DR 8 is commonly associated with these three disorders, and HLA-B7 is also associated with overlap syndrome in Japanese patients. The present case suggested the possibility of a common etiological background for these three disorders. Furthermore, the importance of genetic background, including HLA phenotype, in determining susceptibility to these disorders was demonstrated.