A clinicopathological study on the associations between ranulas and autoimmune diseases.

The study aimed to investigate autoimmune disease (AD) prevalence in ranula patients, analyse their clinicopathological features, and explore the associations between ADs and ranulas. This cross-sectional study enrolled surgically treated ranula patients between 2021 and 2023. AD diagnosis was established. Clinical, serological, and histopathological features were compared. Among the 102 patients, 36.3% had confirmed ADs (predominantly primary Sjögren syndrome and undifferentiated connective tissue disease), 42.2% had no ADs, and 21.6% were suspected of ADs. In the confirmed AD group, 83.8% developed ranulas before AD diagnosis, and exhibited higher female proportion, older age, reduced salivary function, and positive autoantibodies versus the non-AD group. Sublingual gland pathology revealed multifocal lymphocytic infiltration, fatty replacement, ductal epithelial destruction, and periductal collagen proliferation in confirmed and suspected AD groups, rarely in the non-AD group. Focus score was significantly higher in the confirmed AD group, correlating with mucus extravasation foci (r = 0.718, P < 0.01). Grade 3/4 lesions (Chisholm-Mason system) and lymphoepithelial lesions were significantly associated with ADs (P < 0.001, P = 0.033, respectively). In conclusion, a significant proportion of ranulas are associated with ADs, with distinct clinicopathological features. Characteristic histopathological changes in the sublingual gland may indicate ADs, which could potentially contribute to ranula development.