Classification criteria for secondary Sjögren's syndrome. Current state of knowledge

Dryness of mucosa and eyes is the most recognizable symptom of Sjögren's syndrome (SS). Secondary SS (sSS) is diagnosed when symptoms of SS coexist with other systemic connective tissue disease. The sSS is often identified based on the symptoms of dryness in the presence of other connective tissue disease, making the diagnosis of sSS very subjective. The goal of this work was to summarize previously used and current criteria for the diagnosis of sSS. Classification criteria for sSS, which are universally accepted standards, do not exist. The diagnosis of sSS still depends on the experience of the investigator. Histopathological examination of minor salivary glands appears to be crucial for characterization of patients with sSS due to a specific picture of the disease and repeatability of the test.