Grading of minor salivary gland immuno-histopathology post-allogenic hematopoietic cell transplantation

The oral cavity commonly displays mucosal lichenoid lesions and salivary gland dysfunction, which are considered different chronic Graft-versus-Host Disease (cGVHD) pathophysiology’s. However, diagnostics of salivary gland (sg-)cGVHD are limited. The objectives of the current study are to evaluate the minor salivary gland (MSG) histo-immunopathological profiles post allogenic hematopoietic cell transplantation based on sg-cGVHD criteria. Design: Histopathology was characterized according to two published grading strategies. Firstly, the National Institute of Health (NIH) assessed peri-ductal/acinar infiltration, exocytosis, damage, and fibrosis, and a points-based grading scheme was established (0–16 points, Grade (G) 0 to IV). Second, a modified Sjögren’s Syndrome focus-score with parenchymal damage was also adapted, (0–10 points, Score 0 to 2). 146 MSG biopsies from 79 patients were compared, using the histopathological specific criteria for sg-cGVHD pathology. Quantitative immunohistochemistry for T-cells (CD4, CD8), B-cells (CD19, CD20), monocytic cells (CD68) and dendritic cells (CD1a) were also assessed. Results: The large-scale cohort validated the use of both grading schemes. GIII-GIV and score 2 signified a histopathological diagnosis of “likely” sg-cGVHD. Immunopathological severity was associated with increased T-cells (CD4 and CD8) and monocytic (CD68) infiltrate, with minimal involvement of B-cells (CD19 and CD20), and Langerhans cells (CD1a). Conclusions: Both schemes were verified as being suitable for histological grading to improve assessment and diagnosis of sg-cGVHD. The NIH cGVHD grading appears to be more beneficial for research purposes, including final diagnostics of “no/inactive”, “possible” or “likely” cGVHD. The study highlights the intricacies of sg-cGVHD pathology; and the need for standardized assessment to improve patient management associated to sg-cGVHD.