Normal-Appearing Salivary Gland Ultrasonography Identifies a Milder Phenotype of Primary Sjögren's Syndrome

Abstract

<b>Objective:</b> Salivary gland ultrasound (SGUS) is emerging as a valid tool in the management of primary Sjögren's syndrome (pSS). This study aimed to investigate whether pSS patients with normal-appearing or pathological SGUS findings showed different clinical, laboratory, and pathologic pSS-related features, and to compare the results by using two different SGUS scores. <b>Methods:</b> Consecutive pSS patients, according to the ACR-EULAR classification criteria, were evaluated. Salivary glands were scored using the early 1992 score by De Vita et al. and the latest 2019 OMERACT score, both being semiquantitative 0-3 scoring systems focused on ultrasonographic parenchymal inhomogeneity (grades 0 and 1, normal-appearing; grades 2 and 3, pathological). The patients were then divided into two groups: "SGUS normal-appearing" if all the salivary glands had normal-appearing parenchyma (grade 0 or 1), or "SGUS pathological" if the grade was 2 or 3 in at least one salivary gland. The associations between SGUS and pSS-related clinical, laboratory, and pathological features were then investigated in the two groups. <b>Results:</b> One hundred pSS patients were evaluated, the mean age (±SD) was 60.9 ± 12.0 years, and mean disease duration was 11.7 ± 7.2 years. Twenty-nine out of 100 (29%) patients were in the "SGUS normal-appearing" group and 71/100 (71%) were in the "SGUS pathological" group. A normal-appearing SGUS was significantly associated with the absence of anti-La/SSB antibodies (<i>p</i> < 0.001) and normal unstimulated salivary flow rate (<i>p</i> = 0.02) by both univariate and multivariate analyses. By univariate analysis, a normal-appearing SGUS was significantly associated also with the absence of rheumatoid factor (<i>p</i> = 0.002) and of serum monoclonal component (<i>p</i> = 0.003), ESSDAI < 5 (<i>p</i> = 0.03), and with a negative lip biopsy (<i>p</i> = 0.029). No associations were found with other items, including anti-Ro/SSA (<i>p</i> = 0.145), Schirmer's test (<i>p</i> = 0.793), ESSPRI (<i>p</i> = 0.47), and demographic data. No differences in these results were observed by using the two SGUS scoring systems. <b>Conclusion:</b> The SGUS allowed the identification of different phenotypes of pSS, and different SGUS scores focused on salivary gland inhomogeneity may be effective to this end.