Salivary gland ultrasound: From standard protocols to clinical impact in rheumatology

Ultrasound of the salivary and parotid glands has become a valuable tool in rheumatology, especially in the assessment of patients with sicca symptoms, including those with Sjögren's syndrome (SjS). This imaging modality offers a non-invasive approach with proven sensitivity for diagnosis, disease differentiation, and treatment response assessment. This article presents a comprehensive literature review on the use of salivary gland ultrasound (SGUS) in various conditions associated with sicca symptoms, focusing on its application in SjS and other diseases like sarcoidosis, IgG4-related disease (IgG4-RD), and amyloidosis. We summarize the SGUS protocol, normal and pathological findings, and the OMERACT scoring system that standardizes SGUS interpretation. Studies show SGUS provides significant diagnostic support in SjS, with potential utility in assessing other connective tissue and infiltrative diseases, although its role in non-SjS conditions remains under study. Further validation is needed to define its role in clinical algorithms, especially in non-SjS etiologies, and to establish its prognostic value in treatment response. SGUS may improve the sensitivity and specificity of established diagnostic criteria, though it does not entirely replace biopsy in certain cases. Future research should further validate SGUS in diverse rheumatic conditions.