Can ultrasound of the major salivary glands assess histopathological changes induced by treatment with rituximab in primary Sjogren's syndrome?

With great interest we have read the recent publication by Fisher et al ,1 entitled ‘Effect of rituximab on a salivary gland ultrasound score in primary Sjogren’s syndrome: results of the TRACTISS randomised double-blind multicenter substudy’ in which the authors demonstrated a significant improvement in total ultrasound score (TUS) after rituximab treatment compared with placebo at weeks 16 and 48 in 52 patients with primary Sjogren’s syndrome (pSS). We and others have shown that treatment with rituximab, a chimeric anti-CD20 monoclonal antibody, affects the histopathology of the salivary glands and results in a decrease in area of lymphocytic infiltrate in the labial and parotid glands.2–5 This reduction in infiltrated area, that is, up to 50%, is mainly caused by B cell depletion.2 Rituximab treatment also causes a significant loss of germinal centres.2 Interestingly, rituximab treatment also leads to a significant restoration of the ductal epithelium glandular tissue itself. This is illustrated by a significant decrease in number and severity of lymphoepithelial lesions (LELs) in parotid gland tissue 12 weeks after rituximab treatment.2 6 The normalisation of the epithelium appears to be a direct consequence of depletion of intraepithelial B cells.7 Significant improvement of the parotid gland ultrasound score of patients with pSS has been observed before in another randomised controlled trial (RCT) with rituximab, the Tolerance and Efficacy of Rituximab in Primary Sjogren’s Syndrome (TEARS) study.8 This is an RCT with rituximab versus placebo, performed by a French group. Together with the improvement of the histopathology of the gland, it might not be a surprise that Fisher et al 1 also observed a significant improvement in TUS. This newly …