POS1244 ROLE OF MINOR SALIVARY GLAND HISTOLOGY IN PATIENTS WITH SJÖGREN’S SYNDROME: A MONOCENTRIC CROSS-SECTIONAL OBSERVATIONAL STUDY
Authors: S. Colafrancesco, M. Villa, E. Simoncelli, B. Cerbelli, C. Giordano, R. Izzo, L. Mastromanno, I. Fischetti, A. Gattamelata, F. Conti, R. Priori
Journal: Annals of the Rheumatic Diseases (2024)

<h3>Background:</h3> In patients with Sjögren's Syndrome (SS), the biopsy of minor salivary glands (MSG) is a fundamental diagnostic and prognostic tool. However, there is still variability in the histological parameters considered, and the clinical/laboratory associations are yet to be clarified. <h3>Objectives:</h3> Aim of this study is to investigate in a large monocentric cohort of primary SS patients (Sjogren Clinic at University of Rome Sapienza), the predictive value of MSG histology versus the main clinical, clinimetric and laboratory features. <h3>Methods:</h3> Primary SS patients undergoing MSG biopsy between 2016 and 2023 were retrospectively enrolled and the histological/clinical/clinimetric/laboratory data were collected. Histological analysis comprised: focus score (FS) and n° of foci calculation, germinal centers (GCs) [nodular aggregates (H&amp;E), confirmed by CD21+ or Bcl6+ (IHC)] and lymphoepithelial lesions (LEL) (CD20+ IHC in ducts) detection and fibrosis (H&amp;E) recognition. Logistic and linear regression analyses were performed to evaluate the predictive value of histology on clinical/clinimetric/laboratory parameters. <h3>Results:</h3> Two-hundred and thirty-two SS patients were enrolled [mean age 53.6 years (±13.6), F=223/M=9] (figure 1). Both the FS and the n° of foci were predictive of anti-La/SSB, RF, hypergammaglobulinemia and were positively correlated with the ESSDAI. Wile the FS was predictive for low C4 levels, the n° of foci was predictive for anti-Ro/SSA, monoclonal component, biologic and glandular ESSDAI domains. As we recently published [1], a lower FS and n° of foci was predictive for the presence of autoimmune thyroiditis. We found a large agreement between CD21+ and Bcl6+ staining. The presence of GCs (either CD21+ or Bcl6+) was predictive for those serological features associated with a more severe disease. GCs were also predictive of specific ESSDAI domains linked with higher risk of lymphoproliferative complications (Figure 1). Both the CD21+ and the Bcl6+ stainings were predictive of an higher ESSDAI score. Compared to GCs, LEL were even more predictive of different serological features and ESSDAI domains (Figure 1). Interestingly, the presence of fibrosis was associated with a lack of anti-Ro/SSA-La/SSB antibodies. Three patients developed MALT lymphoma; all of them had GCs (CD21+/Bcl6+) and LEL in their MSG biopsies, none had fibrosis [n° of foci: mean=8.3 (SD:5-13); FS mean=3.6 (SD=2.12-4.88)]. <h3>Conclusion:</h3> This is one of the largest studies evaluating the predictive value of histology versus different clinical, clinimetric and laboratory parameters of patients with primary SS. Our data confirm the association between a higher FS and the presence of both serological features known to be linked to a more severe disease and higher ESSDAI score values. Compared to the FS, the number of foci revealed additional associations such as the biological and glandular ESSDAI domains. We confirm the association between GCs and those serological/clinical features accompanying a more systemic and active disease and we provide evidence of the same, and also additional associations, for the LEL. Finally, we demonstrate for the first time that the presence of fibrosis may be predictive of seronegative patients; this relevant finding, is currently under validation on a larger cohort. <h3>REFERENCES:</h3> [1] Colafrancesco S, et al. Clinical and histological features of patients with primary Sjögren's syndrome and autoimmune thyroiditis: a national multicentre cross-sectional study. Clin Exp Rheumatol. 2023;41(12):2389-2396. <h3>Acknowledgements:</h3> <b>NIL.</b> <h3>Disclosure of Interests:</h3> <b>None declared.</b>