OP0297 DIAGNOSTIC VALUE OF LABIAL MINOR SALIVARY GLAND BIOPSY IN THE DIAGNOSIS OF SJÖGREN’S SYNDROME: HISTOLOGIC FINDINGS OF 678 BIOPSIES AND ASSOCIATIONS WITH LABORATORY MARKERS, CLINICAL AND PATIENT ASSOCIATED PARAMETERS.

Abstract

BackgroundHistologic findings of salivary gland biopsy are a crucial part of the current ACR-EULAR classification criteria of Sjögren’s cyndrome (SS) (1). Particularly, the finding of a focal lymphocytic sialadenitis (focus score ≥ 1/4 mm2) corresponds to 3 scoring points out of 4 needed to reach a positive classification for SS [1]. Moreover, there is increasing evidence that salivary gland biopsy can provide prognostic information regarding systemic involvement and the development of lymphoma in the context of the disease.ObjectivesThe aim of this study was to analyze the minor labial salivary gland (MLSG) biopsy findings of a large SS cohort and to examine their associations with disease specific laboratory markers, clinical and patient associated parameters.MethodsWe included all patients from two large rheumatological medical departments in Germany having undergone a diagnostic MLSG between 01/2010 and 12/2019. The data have been collected partly in a retrospective and party in a prospective manner. Next to the examination of histological results we focused on activity and chronicity parameters of the underlying disease, autoantibodies, presence of systemic and haematological involvement, as well as on current and previous comorbidities. The statistical analyses included sensitivity and specificity examinations via receiver operating characteristics (ROC), correlation analyses, Mann-Whitney-U-Tests and ANOVA.ResultsIn total, 678 patients have been included (615 ♀, median age 55 years [47-63, IQR]). 306 patients (45.1%) had a positive focus score. The remaining 372 patients with a negative focus score served as a control group. There were significant correlations between the level of the focus score and nicotine use (p=0.002), hypergammaglobulinemia [1.27 (0.71-3.36, IQR) vs. 0.73 (0.0-0.76, IQR); p<0.001], ANA positivity [1.18 (0.11-3, IQR) vs. 0.64 (0-1.34, IQR); p<0.001] and rheumatoid factor positivity (p<0.001). Moreover, focus score levels correlated significantly with disease modifying antirheumatic treatment [1 (0-2.34, IQR) vs. 0.87 (0-1.8, IQR); p=0.004] and weakly significantly with erythrocyte sedimentation rate (r=0.235, p<0.001).Within the group of patients with primary SS there were significant correlations between the level of the focus score and presence of systemic involvement [2 (1.1 - 4, IQR) vs. 1.44 (1-2.62, IQR); p=0.015], glandular involvement [4 (2.98-6.2, IQR) vs. 0.72 (1.6-3, IQR); p=0.007] and haematologic manifestations (p=0.002). SSA-antibodies showed the best diagnostic performance compared to MLSG, as examined by ROC (Table 1).Table 1.Diagnostic value of SSA-antibodies, Sicca, Schirmer´s and Saxon´s test compared to minor labial salivary gland biopsy findings (reference focus score ≥ 1/ 4 mm2)SpecificitySensitivityArea under the curveSSA-Ro antibodies88.2%43.4%0.658Sicca15%91.9%0.535Schirmer´s test27.3%73%0.507Saxons´s test57.9%39%0.541Interestingly enough, among 159 patients who were admitted due to the diagnosis of primary fibromyalgia (FM), 63 (39.6%) could be diagnosed with SS on the basis of histologic findings and the ACR-EULAR classification criteria.ConclusionBy examining one of the largest cohorts in the literature we could show that MLSG biopsy findings not only play a key role in the classification and diagnosis of SS, but could also provide important information regarding the presence of a systemic, glandular or haematological involvement. Furthermore, MLSG can help differentiate patients with FM and other chronic pain disorders from patients with subclinical SS who suffer primarily from chronic pain.