Diagnostic and Prognostic Features of Sjögren’s Syndrome

Sjögren’s syndrome (SS) is a chronic autoimmune disease characterized by the lymphocytic infiltration of salivary and lacrymal glands leading to xerostomia and keratoconjunctivitis sicca (KCS). The prevalence of SS is variable but recent studies have estimated it to be between 0.1-0.6%(Goransson et al., 2011; Trontzas & Andrianakos, 2005). As such, SS occurs in middleaged patients with a high female predominance of 9 to 1 (Fox, 2005). SS is classified either as primary (pSS) when occurring alone or secondary (sSS) to other autoimmune diseases such as rheumatoid arthritis or systemic lupus erythematosus. Besides the involvement of exocrine glands entailing the classical sicca syndrome, systemic manifestations resulting from the lymphocytic infiltration of organs can be present in up to 20% of cases. There are actually no specific diagnostic criteria for SS, but for clinical studies and teaching purposes, SS is classified according to the American-European classification criteria, which include subjective and objective criteria of xerostomia and KCS as well as the presence of autoimmune antibodies and histopathological salivary gland involvement. Because of the lack of a “gold standard” for SS, the standard of reference being actually used is clinical diagnosis made by an experienced clinician. The lack of specific diagnostic tests combined with the high frequency of sicca symptoms in the general population makes the diagnosis of SS even more complicated. This holds true especially in early disease where the symptoms and signs are usually mild and might explain the time delay for the diagnosis of SS. The importance of making the diagnosis of pSS is cardinal because of the increased risk of developing lymphoma and serious systemic complications. In an endeavor to increase the likelihood of diagnosis of SS, newer diagnostic tools have been devised such as ultrasound sonography of salivary glands, magnetic resonance imaging of parotid glands as well as epigenetic biomarkers.