The Parotid Gland in Primary Sjögren Syndrome: Association of Ultrasound, Histopathology and Saliva Production in the Diagnostic Workup

Abstract

Objectives: The parotid glands are commonly involved in primary Sjogren syndrome (pSS). The aim of this study was to assess the diagnostic accuracy of ultrasound of the parotid glands (PSGUS) compared with parotid histopathology and parotid saliva production. Study Design: We included consecutive patients suspected to have pSS. All patients underwent a full diagnostic workup according to American College of Rheumatology– European League Against Rheumatism (ACR-EULAR) criteria, including PSGUS, parotid gland biopsy, and collection of stimulated parotid saliva. For PSGUS, the average score of hypoechogenic areas in both parotid glands was applied (range 0-3). On hematoxylin and eosin (HE P < .001) and percentage of lymphocytic infiltrate (ρ = 0.575; P < .001). There was a moderate to good absolute agreement between the PSGUS and focus scores (78.5%), plasma cell shift (79.8%), LELs (81.4%), and GCs (82.7%). “Presence of hypoechogenic areas” was not very sensitive to predict focus score (69.2%), plasma cell shift (45.8%), LELs (61.5%), or GCs (34.6%). Interestingly, almost all patients with less than 25% presence of hypoechogenic areas in glandular parenchyma were also negative for GCs (98.7%). A substantial number of these patients did not have a positive focus score (81.4%), plasma cell shift (90.7%), or LELs (87.8%). There was a fair reversed correlation between PSGUS and stimulated parotid saliva flow (ρ = −0.259; P = .07). Conclusions: This is the first study comparing the diagnostic accuracy of PSGUS with histopathology and salivary secretion in detail. PSGUS and histopathology have a stronger association compared with PSGUS and parotid secretion. The specificity of PSGUS increases when the results are compared with plasma cell shift, LELs, and GCs, rather than with the focus score.