Clinical and serological characteristics of seronegative primary Sjögren's syndrome: a comparative study.

The clinical features of seronegative pSS (i.e., a lack of four autoantibodies in serum) were similar to those of seropositive pSS. The current classification criteria for pSS should not be used in the diagnosis of seronegative pSS, as the agreement between the different sets of criteria was low, and some patients fell outside the classification. Further clinical and laboratory studies are needed to identify the features that distinguish seronegative pSS. Key Points • Approximately 15% of the pSS patients were seronegative for ANA, RF, anti-Ro, and anti-La autoantibodies. • Seronegative pSS was diagnosed based on lymphocytic infiltrations in lip biopsy samples. • The clinical features of seronegative pSS were similar to those of seropositive pSS. • The current classification criteria for pSS should not be used in the diagnosis of seronegative patients, as the agreement between the different sets of criteria was low, and some patients fell outside the classification.