The lacrimal gland in Sjögren's syndrome: can we unravel its mystery using ultrasound?

According to a recent survey of patients with the autoimmune disease primary Sjögren's syndrome (pSS), dry eye symptoms are present in 95-98% of pSS patients. As one of the most disabling symptoms mentioned by pSS patients, dry eyes have demonstrable effects on quality of their life, leading to eye dryness, itching, and pain, with some patients describing as a recurrent sensation of sand or gravel in the eyes. The symptoms are matched only in prevalence by dry mouth and chronic fatigue. In contrast to the prevalence of dry eye symptoms in pSS and their burden on pSS patients, our comprehension of dry eye disease development is minimal; specifically how function of the tear-fluid producing gland the lacrimal gland (LG), manifests. The comparison becomes stronger again when we consider what we know about dysfunction of the salivary gland (SG) in pSS, for example the appreciation of the transcriptome of 'innately activated' B cells invading the SG, their complicity in formation of lymphoepithelial lesions, and the ability of the SG epithelium to actively contribute to the inflammatory milieu. The exploration of ultrasound imaging as an additional modality to garner information about SG dysfunction in pSS has opened many doors for non-invasive, repeatable imaging in pSS. Here we summarise SG histology and ultrasound phenotype briefly and then juxtapose this with available studies examining LG pathology and ultrasound, and our understanding of LG dysfunction in pSS.