Salivary gland ultrasound reveal similarities among Sjögren's syndrome, sarcoidosis, amyloidosis
Sjögren’s syndrome, sarcoidosis and systemic immunoglobulin light chain amyloidosis all share common features when analyzed through salivary gland ultrasound, according to findings published in Arthritis Care & Research.
“Ultrasound is becoming substantially more popular for imaging of salivary glands in the rheumatology community,” Eugene Kissin, MD, of Boston University Medical Center, told Healio Rheumatology. “The number of citations in PubMed on this topic has increased from 7 in 2002 — when I first started learning musculoskeletal ultrasound — to 37 last year.
With the increased attention, there is a danger of overestimating the specificity of salivary gland ultrasound imaging for Sjögren’s syndrome, since this if the condition to which salivary gland ultrasound imaging has been most commonly applied and studied by rheumatologists.”
To analyze the diagnostic accuracy of major features visible in salivary gland ultrasound that differentiate between Sjögren’s syndrome from sarcoidosis, amyloidosis and a control group, Kissin and colleagues conducted a cross-sectional study of adult patients at Boston Medical Center. The researchers recruited consecutive outpatient participants — including 21 with Sjögren’s syndrome, 27 with sarcoidosis, 22 with AL amyloidosis and 16 individuals without these or any other autoimmune rheumatic disease — between June 2017 and May 2018.
All patients with Sjögren’s syndrome, sarcoidosis or AL amyloidosis were either positive anti-SSA, anti-SSB or had a typical minor salivary gland biopsy. Participants underwent salivary gland ultrasound by a single, blinded researcher using the Hoevar protocol. Further, participants completed sicca symptom questionnaires related to symptoms of dryness, Schirmer’s test and an unstimulated salivary flow measurement. Another blinded researcher analyzed the ultrasound video clip images for salivary gland ultrasound score, hyperechoic septae and other characteristics.
According to Kissin and colleagues, patients with Sjögren’s syndrome demonstrated greater salivary gland ultrasound scores than participants in other groups. However, there were no features in the salivary glands that distinguished Sjögren’s syndrome from AL amyloid or sarcoidosis. None of the participants in the control group had a salivary gland ultrasound score greater than 17, a threshold previously suggested for Sjögren’s syndrome, the researchers wrote. Meanwhile, 27% of patients with AL amyloidosis and 19% of those with sarcoidosis patients scored higher than 17.
The researchers also found that adding a Hoevar salivary gland ultrasound score of 17 or greater to the 2016 American College of Rheumatology/EULAR criteria in parallel scheme increased sensitivity for Sjögren’s syndrome from 87% to 98%. Combining the two criteria in series increased specificity from 81% to 98%.
“Our study points out the similarities in sonographic appearance among salivary glands in patients Sjögren’s syndrome, sarcoidosis, and AL amyloidosis,” Kissin said. “These latter two conditions may also be encountered by rheumatologists though less frequently than Sjögren’s syndrome.” – by Jason Laday
Disclosure: The researchers report no relevant financial disclosures.