The parotid gland connection: ultrasound and biopsies in primary Sjögren’s syndrome

We would like to thank Alegria et al 1 for their letter to the editor commenting on our recent publication entitled ‘Ultrasonography of major salivary glands compared with parotid and labial gland biopsy and classification criteria in patients with clinically suspected primary Sjogren’s syndrome’.2 Our study was the first that directly compared the validity of ultrasound of major salivary glands (sUS) with parotid gland biopsy outcome. We showed that the agreement between sUS and parotid as well as labial gland biopsies was good but was slightly higher for the former. As noted by Alegria et al ,1 we found different results for the positive predictive value (PPV) and negative predictive value (NPV) between sUS versus parotid and sUS versus labial gland biopsies.2 Although these observations may indeed be caused by discordance between the parotid and labial gland biopsy outcome, there are other factors that may equally well contribute to this discrepancy. First, the parotid glands are assessed during the sUS examination and included in the scoring, whereas the labial glands are not.2 Second, in 6%–15% of the general population, the labial gland biopsy is positive, while in only 5% of the general population, the parotid gland biopsy is positive. …