Ultra-high frequency ultrasonography (UHFUS) has been recently introduced in oral medicine due to its ability to image small anatomical structures including labial salivary glands (LSG). To date no ultrasonography morphological studies of labial salivary glands (LSG) have been carried out in SS. In this pilot study we aimed at analysing the distribution of UHFUS findings in LSG of patients with suspected SS, focusing in particular on the association with patients' oral dysfunction, antibody profiles and histopathology.
Consecutive patients undergoing a LSG biopsy for clinically suspected SS were included in this study between January 2018 and January 2020. Intraoral UHFUS scan of the lip mucosa was performed with Vevo MD equipment, using a 70 MHz probe with a standardised protocol. LSG were assessed by using a four-grade semiquantitative scoring system (0-3), similar to the OMERACT scoring system used for major salivary glands. The distribution of UHFUS grades was compared in patients stratified according their final diagnosis, patients antibody profiles and LSG histopathology.
We included 128 patients with suspected SS: out of them, 54 (42.2%) received a final diagnosis of SS, made according to the ACR 2016 criteria and 74 (57.8%) were diagnosed as no-SS sicca controls. We found that LSG inhomogeneity was significantly greater in patients with SS than in no-SS subjects (p<0.0001). We also found that higher UHFUS pattern of inhomogeneity (i.e. grade 2 and 3) were significantly more frequent in both SSA+/SSB- and SSA+/SSB+ patients (p=0.001). A normal UHFUS pattern, by contrast, was significantly more common in SSA-/SSB- subjects (i.e. 15/83 (18.1%) vs. 1/33 (3%) vs. 0/12 (0%), p=0.001). Finally, LSG inhomogeneity was significantly associated with both the number of foci (p<0.001) and focus score (p<0.001). Particularly, we found that both the number of foci and the FS were significantly higher in patients presenting a UHFUS grading of 2 and 3 with respect to those presenting a UHFUS grading of 0 and 1 (p=0.01).
This preliminary study demonstrates the optimal feasibility of UHFUS and its high sensitivity in identifying negative patients on subsequent lip biopsy, thus avoiding invasive procedures in selected cases. Further studies are in progress to define the clinical and predictive role of the various patterns observed and their added value with respect to traditional salivary gland ultrasonography.