Primary Sjögren's syndrome.

Primary Sjögren's syndrome (pSS) is a systemic autoimmune disorder characterized by focal lymphocytic infiltration of the exocrine glands causing dry eyes and dry mouth. Similar glandular features can also occur as a late complication in patients with other rheumatic disorders, such as rheumatoid arthritis (RA), systemic lupus erythematosus (SLE) and scleroderma ('secondary' Sjögren's syndrome). Anti-Ro and/or anti-La (ENA) antibodies are found in approximately 70% of pSS patients, generally with ANA positivity. Hypergammaglobulinaemia is also common. Systemic features also occur in some patients with pSS. A positive rheumatoid factor (RF) is often seen and so if patients present with arthritis, dryness and a positive RF a diagnosis of pSS should be considered as a possible alternative to RA. Anti-CCP antibodies are more specific for RA.