Diagnostic Performance of Parotid Shear-Wave Elastography for Predicting Histopathological Positivity in Patients with Suspected Primary Sjögren’s Syndrome

Background: Primary Sjögren’s syndrome (pSS) is a chronic autoimmune epithelitis characterized by lymphocytic infiltration of the exocrine glands. Although labial salivary gland biopsy remains the reference standard for diagnosis, it is invasive and may not always be feasible in routine practice. This study aimed to evaluate the diagnostic performance of parotid gland shear-wave elastography (SWE) and to investigate its relationship with histopathological findings in patients with suspected pSS. Methods: This prospective study included 93 participants (53 patients with pSS and 40 controls). Shear-wave elastography measurements of the parotid glands were obtained, and their association with histopathological findings was analyzed. Diagnostic performance was assessed using receiver operating characteristic (ROC) analysis. Multivariable logistic regression was performed to evaluate independent predictors of histopathological positivity. Results: Mean shear-wave elastography velocity values (m/s) were significantly higher in the pSS group than in controls (p < 0.001), and this difference remained significant after adjustment for age (adjusted β = 2.141, p < 0.001). ROC analysis demonstrated moderate discriminative performance for predicting histopathological positivity (AUC = 0.76, 95% CI: 0.61–0.89). The optimal cut-off value of 2.17 m/s yielded a sensitivity of 69.0% and a specificity of 94.1%. A moderate positive correlation was observed between right parotid elastography values and histopathological grade (r = 0.483, p < 0.001). In multivariable analysis, elastography mean and anti-SSA positivity showed positive but non-significant associations with histopathological positivity. The model demonstrated good calibration (Hosmer–Lemeshow p = 0.866) and high apparent discrimination (AUC = 0.947), with reduced performance after internal validation. Conclusions: Parotid shear-wave elastography is a non-invasive imaging method with moderate diagnostic performance in pSS. Elastography measurements correlate with histopathological involvement and remain significantly elevated after age adjustment. SWE may serve as a complementary tool for pre-biopsy risk stratification, particularly when biopsy is contraindicated or declined. Further validation in larger, independent cohorts is required.