Ultrasonography of major salivary glands: a highly specific tool for distinguishing primary Sjögren's syndrome from undifferentiated connective tissue diseases

OBJECTIVES: Recently, convincing data have been published on the value of salivary gland ultrasonography (SGUS) in differentiating primary SS from non-immune-mediated sicca syndrome. Limited data are available regarding the diagnostic accuracy of SGUS in distinguishing SS from other rheumatic diseases. The purpose of this study was to assess the usefulness of SGUS in distinguishing patients with SS from those with xerostomia and/or xerophthalmia and a diagnosis of stable UCTD. METHODS: This cross-sectional study consecutively enrolled 150 patients either diagnosed with SS (as established by the American-European Consensus Group criteria) or affected by UCTD but not SS. Parotid and submandibular glands on both sides were assessed for size, parenchymal echogenicity and inhomogeneity by means of SGUS, which was performed by a radiologist blinded to the diagnosis. Echostructural alterations of the salivary glands were graded from 0 to 3 (cut-off >2). RESULTS: This study included 109 patients: 55 with SS and 54 with UCTD. Patients with SS showed a higher SGUS score in comparison with those with UCTD [mean 2.2 (s.d. 1.8) vs 0.2 (s.d. 0.5), P < 0.0001]. The SGUS cut-off >2 showed a sensitivity of 65%, a specificity of 96%, a positive predictive value of 95% and a negative predictive value of 73% for SS diagnosis. A significant correlation was also found between the SGUS score and the minor salivary gland biopsy/focus score (r = 0.484, P < 0.0001). CONCLUSION: This study confirmed the good sensitivity and the high specificity of SGUS in differentiating SS from other CTDs.