AB0333 USEFULNESS OF MULTI-PARAMETRIC EVALUATION INCLUDING MINOR SALIVARY GLAND BIOPSY FOR THE DIFFERENTIAL DIAGNOSIS OF SICCA SYNDROME IN A SPANISH SINGLE-CENTER EXPERIENCE

Background: Sjogren’s syndrome (SS) is a systemic autoimmune disease characterized by mononuclear cell infiltration of the exocrine glands, which leads to sicca syndrome and systemic manifestations. The minor salivary gland biopsy (MSGB) is undoubtedly important for the classification, diagnosis and prognosis of SS. However, differentiating SS and non-Sjogren’s sicca syndrome (NSS) can be challenging. Objectives: The aim was to evaluate the histological characteristics of MSGB besides focus score (FS) in patients with sicca syndrome and the usefulness of the different clinical, serological and histological parameters to diagnose, classify and describe the prognosis of patients with Sjogren’s syndrome. Methods: Prospective observational single-center study of patients referred for study of sicca syndrome with multi-parametric evaluation from January 2019 to December 2020. A diagnostic protocol based on Schirmer’s test, unstimulated whole salivary flow (UWSF) and minimally invasive MSGB was applied. Patients fulfilling 2016 ACR-EULAR classification criteria were classified as SS. Results: In a cohort of 115 patients with sicca syndrome, 55 (47.8%) were diagnosed with SS. The mean age was 56.9±14.5 years and most of the patients were women (81,7%) with no significant differences between SS and NSS. SS were more likely to present positive Schirmer’s test, positive UWSF, anti-Ro+, FS≥1, antinuclear antibodies (ANA+), rheumatoid factor (RF+) and anti-La+ among others. MSGB was a safe procedure and very effective (only 7% insufficient biopsies) in our cohort. The mean gland size of the MSGB was 5.7±0.37 mm2. Furthermore, it was the individual parameter that most correlated with SS, even more than anti-Ro+, Schirmer’s and UWSF. Seronegative SS (Anti-Ro-) was 47.3%. These patients could not have been diagnosed except by MSGB. Scintigraphy did not help to differentiate SS from NSS, neither patient-referred xerostomia nor xerophthalmia. The most frequent histological diagnosis was focal lymphocytic sialadenitis (FLS) (81.8%) followed by nonspecific chronic sialadenitis (9.1%). However, only FLS had a correlation with SS. There were no MSGBs labeled normal among the SS patients. Mean FS was 2.22±0.2 (16.7% had FS≥3). The rest of the histological parameters that showed a positive correlation with SS were glandular atrophy (GA), germinal centers (GC), lymphoepithelial lesions (LEL) and lymphoid follicles (LF). FS≥1 is the current histological classification criteria for ACR/EULAR. However, the presence of lymphocytic infiltrates (LI) (although not FS≥1) and FLS were suggestive markers of SS with greater sensitivity (SE) and specificity (SP). FS≥3, GC, LEL and LF were only found in SS and were associated in previous studies with higher risk of lymphoma and systemic disease. Conclusion: SS is a heterogeneous disease that requires a comprehensive clinical, serological, functional and histological evaluation. MSGB is a simple, safe, repeatable procedure that provides enormous information. It was the single parameter that best correlated with SS and allowed the diagnosis of seronegative SS. In summary, the use of MSGB is essential not only for the differential diagnosis of sicca syndrome but also as a prognostic marker for SS. References: : [1]Bautista-Vargas et al. Autoimmun Rev. 2020 Dec;19(12):102690. Disclosure of Interests: None declared