Minor salivary gland biopsies in childhood-onset Sjögren’s disease show greater inflammation and more frequent fibrotic changes than in adult-onset Sjögren’s disease

To provide the first histopathological characterization of minor salivary gland (MSG) biopsies in childhood-onset Sjögren’s disease (cSjD) in comparison with adult Sjögren’s disease (SjD). MSG biopsies obtained by eighteen consecutive children fulfilling the 2016 ACR/EULAR classification criteria for SjD and 55 consecutive adult SjD patients were analysed. Clinical features, ESSDAI, ESSPRI, and salivary gland histopathology were collected according to EULAR standards, including focus score (FS), lymphoepithelial lesions (LELs), and ectopic germinal centers (GCs) by immunohistochemistry. Compared with adults, children showed a more inflammatory phenotype. Recurrent parotid swelling was significantly more frequent in cSjD (38.9% vs. 5.5%, p = 0.0015), whereas xerostomia and xerophthalmia predominated in adults ( p < 0.0001 for both). Palpable purpura was more common in children (44.4% vs. 1.8%, p < 0.0001), while fatigue and myalgia were rare ( p = 0.0058 and p < 0.0001, respectively). Rheumatoid factor was more prevalent in cSjD (77.7% vs. 30.9%, p = 0.0072), whereas anti-SSA antibodies were less frequent ( p = 0.0029). ESSDAI scores were higher ( p = 0.0001) and ESSPRI lower ( p < 0.0001) in children, reflecting greater systemic inflammation but lower subjective symptom burden. Pediatric biopsies exhibited higher FS than adults (median 3.4 vs. 1.0, p = 0.0002), together with more frequent GCs (44.4% vs. 5.5%, p = 0.00034), LELs (61.1% vs. 5.5%, p < 0.0001), and fibrotic changes (66.7% vs. 27.3%, p = 0.0048). Quantitative immunohistochemistry further showed significantly increased CD3 and CD20 lymphocytic infiltrates in cSjD biopsies, together with an increased CD20/(CD20 + CD3) proportion (all p < 0.0001). MSG biopsies in cSjD show a more inflammatory, lymphoid-organizing B-enriched phenotype, with more frequent fibrosis than in adults. These findings are in keeping with previous observations in pediatric parotid tissue and highlight frequent fibrotic remodelling alongside marked inflammation despite shorter disease duration in children.