Primary Sjögren's syndrome with type II respiratory failure caused by myotonic dystrophy type 1: A case report and literature review.

Primary Sjögren's syndrome (pSS) is an autoimmune disease characterized by the involvement of exocrine glands with dryness of mouth and eyes as typical clinical manifestations, and may also have extra-glandular organ involvement. Myotonic dystrophy type 1 (DM1) is the most common type of adult-onset muscular dystrophy, which can lead to progressive muscle weakness and myotonia. The coexistence of pSS with DM1 was rarely reported. We here report a Chinese female pSS patient with progressive type II respiratory failure as a major manifestation and finally diagnosed with DM1 by genetic testing.