OP0105 ULTRASOUND GUIDED CORE-NEEDLE BIOPSY OF THE UNSWOLLEN PAROTID GLAND IS A RELIABLE TECHNIQUE IN THE WORK-UP OF PRIMARY SJÖGRENS’ SYNDROME
Authors: H. Achten, E. Genbrugge, A. Vanhaecke, D. Creytens, L. Deroo, K. De Boeck, J. Deprez, E. Dumas, D. Elewaut, I. Peene
Journal: Annals of the Rheumatic Diseases (2024)

<h3>Background:</h3> Ultrasound (US) guided core-needle biopsy (CNB) of the swollen parotid gland showed its value in the risk stratification of primary Sjögren's Syndrome (pSS). <h3>Objectives:</h3> This study assessed the feasibility of US guided CNB of the unswollen parotid gland and the correlation between ultrasonographic and histopathological findings. <h3>Methods:</h3> US-guided CNB was performed in 67 consecutive patients without parotid gland swelling with suspected or confirmed pSS from the Belgian Sjögren's Syndrome Transition Trial (BeSSTT). Standard histopathological assessment was performed for the detection of T-cells (CD3), B-cells (CD20), follicular dendritic cells (CD21), plasmacells (CD138) and focus score (FS). US was evaluated using the OMERACT [1] and Hocevar Score [2]. Pvalues ≤0.05 were considered significant. <h3>Results:</h3> Sufficient salivary gland tissue for FS calculation was obtained in 85% of patients. 9% had less representative biopsies (&lt;4mm<sup>2</sup>) and 5% revealed only adipose tissue. Patients with positive FS, CD21, CD138, or B/T &gt;1 demonstrated significantly higher Omeract and Hocevar scores compared to their negative counterparts (p &lt; 0.01), <b>Figure 1.</b> In the subgroup &lt;4mm<sup>2</sup>, 2/3 patients with maximum Omeract Score showed CD21 or B/T&gt;1 while none of the low Omeract scores exhibited such features. Hocevar and Omeract scores were strongly correlated (Rs=0.87, p&lt;0.001), as well were FS, CD21 positivity and B/T&gt;1. The accuracy of US in predicting a positive FS was good, demonstrating an Area Under the Curve of 0.81 at the cutoff point of a total OMERACT score of ≥8. Within the subgroup with &lt;4mm<sup>2</sup> or not representative biopsies, individuals with an OMERACT score of ≥8 consistently met the pSS ACR-EULAR 2016 classification criteria. <b>Figure 1.</b> According to the histopathology protocol, Mucosa-Associated Lymphoid Tissue (MALT) lymphoma was present in three patients despite the lack of clinically evident gland swelling. These patients presented with maximal OMERACT scores and increased B-cell activity in peripheral blood. No major adverse events from CNB were reported and patients reported a VAS 4/10 during procedure and high willingness (85%) for future application. <h3>Conclusion:</h3> Our study is the largest series evaluating 67 consecutive US-guided CNBs of the unswollen parotid gland in the work up of pSS. Only a minority of biopsies was too small, though our study highlights the importance of considering additional characteristics, such as B/T &gt;1 or CD21 positivity, beyond the universally accepted FS when evaluating parotid gland by CNB. Additionally, US guidance appeared particularly helpful in identifying patients who may benefit from CNB for lymphoma risk stratification. Notably, in cases with prominent B-cell activity markers and maximal OMERACT scores, even in the absence of clinically swollen salivary glands, CNB emerges as a minimal invasive tool for detecting MALT lymphoma in the pre-clinical phase. Hence, CNB has demonstrated minimal invasiveness, good tolerance and significant value in the diagnostic (and therapeutic) evaluation of pSS. <h3>REFERENCES:</h3> [1] Jousse-Joulin S, D'Agostino MA, Nicolas C, Naredo E, Ohrndorf S, Backhaus M, et al. Video clip assessment of a salivary gland ultrasound scoring system in Sjögren's syndrome using consensual definitions: an OMERACT ultrasound working group reliability exercise. Ann Rheum Dis. 2019;78(7):967-73. [2] Hocevar A, Ambrozic A, Rozman B, Kveder T, Tomsic M. Ultrasonographic changes of major salivary glands in primary Sjogren's syndrome. Diagnostic value of a novel scoring system. Rheumatology (Oxford, England). 2005;44(6):768-72. <h3>Acknowledgements:</h3> <b>NIL.</b> <h3>Disclosure of Interests:</h3> Helena Achten: None declared, Eva Genbrugge: None declared, Amber Vanhaecke: None declared, David Creytens: None declared, Liselotte Deroo: None declared, Kristel De Boeck: None declared, Joke Deprez: None declared, Emilie Dumas: None declared, Dirk Elewaut BMS argenx, Isabelle Peene argenx, BMS argenx.