The information about comorbidities (excluding lymphoma) in primary Sjögren's syndrome (pSS) is relatively scarce. Cardiovascular disease, infections, musculoskeletal conditions or malignancy are likely the most relevant comorbid conditions in pSS. Different infections (particularly oral candidal infections) and fibromyalgia are extremely frequent in the daily clinical practice. On the other hand, the incidence of cardiovascular events and cancer in pSS is low, so information about them comes from large epidemiological studies or meta-analysis. For this reason, preclinical vascular disease is investigated by different techniques, demonstrating the presence of early atherosclerosis in pSS patients. Coronary events could be slightly more frequent in pSS than in the general population. The overall risk of malignancy in pSS patients seems to be slightly increased, likely due to excess occurrence of lymphoma. An association between pSS and thyroid cancer might exist, although it should be confirmed by further investigations.

Primary SS (pSS) is a rheumatic disease characterized by an immune-mediated exocrinopathy, resulting in severe dryness of eyes and mouth. Systemic symptoms include fatigue and joint pain and a subset of patients develop more severe disease with multi-organ involvement. Accumulating evidence points to involvement of innate immunity and aberrant activity of the type I IFN system in both the initiation and propagation of this disease. Analysis of the activity of IFN-inducible genes has evidenced that more than half of pSS patients present with a so-called 'type I IFN signature'. In this review, we examine activation of the IFN system in pSS patients and how this may drive autoimmunity through various immune cells. We further discuss the clinical value of assessing IFN activity as a biomarker in pSS patients and review novel therapies targeting IFN signalling and their potential use in pSS.