Standardisation of labial salivary gland histopathology in clinical trials in primary Sjögren's syndrome

Abstract

Labial salivary gland (LSG) biopsy is used in the classification of primary Sjögren's syndrome (PSS) and in patient stratification in clinical trials. It may also function as a biomarker. The acquisition of tissue and histological interpretation is variable and needs to be standardised for use in clinical trials. A modified European League Against Rheumatism consensus guideline development strategy was used. The steering committee of the ad hoc working group identified key outstanding points of variability in LSG acquisition and analysis. A 2-day workshop was held to develop consensus where possible and identify points where further discussion/data was needed. These points were reviewed by a subgroup of experts on PSS histopathology and then circulated via an online survey to 50 stakeholder experts consisting of rheumatologists, histopathologists and oral medicine specialists, to assess level of agreement (0-10 scale) and comments. Criteria for agreement were a mean score ≥6/10 and 75% of respondents scoring ≥6/10. Thirty-nine (78%) experts responded and 16 points met criteria for agreement. These points are focused on tissue requirements, identification of the characteristic focal lymphocytic sialadenitis, calculation of the focus score, identification of germinal centres, assessment of the area of leucocyte infiltration, reporting standards and use of prestudy samples for clinical trials. We provide standardised consensus guidance for the use of labial salivary gland histopathology in the classification of PSS and in clinical trials and identify areas where further research is required to achieve evidence-based consensus.

Keywords: Autoimmunity; Outcomes research; Sjøgren's Syndrome.

Figure 1

Box plot of the 16 agreed points (table 1) on the vertical axis and level of agreement (0–10) on the horizontal axis. The dashed line shows the predefined cut-off for agreement. Boxes indicate first and third quartiles with the internal line indicating the median. Whiskers indicate the minimum and maximum scores given except when considered outliers, whereas circles indicate outliers (≤1st quartile–1.5×IQR) and stars far outliers (≤1st quartile–3×IQR).

Figure 2

(A) Microphotograph illustrating salivary gland biopsy obtained from a patient with primary Sjögren's syndrome, stained with H&E. (B) Image analysis applied to macrosection showing delineation of glandular tissue in red. Focus score is calculated by counting the number of foci, whose area is delineated within the black lines, dividing by the whole glandular surface area in mm² and multiplying by 4 to give the number of foci per 4 mm² over the whole glandular area. In this example, the glandular surface delineated includes interspersed atrophic areas but excludes any attached epithelial or connective tissue. The measured glandular area is 20.89 mm² and there are 8 foci giving a focus score of 1.53. (C) Microphotograph illustrating salivary gland biopsy obtained from a patient with diagnosis of primary Sjögren's syndrome that presents a large area of fibrosis and parenchymal atrophy, alongside areas of focal lymphocytic sialadenitis (original magnification ×20).

Figure 3

(A–H) Sequential sections illustrating inflammatory infiltrates in the salivary glands of patients with primary Sjögren's syndrome stained by H&E (A, C, E), CD3 (brown in B), CD20 (pink in B and brown in G) and CD21 (brown in D, F and H). (A and B) Sequential section illustrating segregation in T and B cells in large periductal infiltrate in absence of germinal centre (GC). (C and D) Evident GC in H&E stained section confirmed by CD21 staining on sequential section. (E and F) Small CD21+ cluster of follicular dendritic cells (FDCs) in sequential section of a large aggregate with absence of obvious GC features at the H&E staining. (G and H) Large CD20+ infiltrate with obvious lymphoepithelial lesions (inset) and the presence of CD21+ FDC networks at the sequential section.