Background primary Sjögren’s syndrome (pSS) is the autoimmune disease with the highest risk of lymphoma. Lymphoma and mixed cryoglobulinemic vasculitis (CV) occur in a minority of cases, but they are the most relevant clinical features characterizing the B cell lymphoproliferation in pSS.
Objectives to provide serological biomarkers associated with lymphoproliferative complications (B-cell lymphoma, cryoglobulinemic vasculitis (CV) and non malignant major salivary gland swelling) in primary Sjögren’s syndrome (pSS).
Methods data in 1170 patients with pSS diagnosis were retrospectively collected. The analyses were then performed in patients fulfilling the following criteria: 1. European or AECG criteria, 2. Hepatitis C virus infection antibody negative, 3. serum cryoglobulins tested. Multinomial analyses (P<0.05) were performed by distinguishing 4 groups: 1. lymphoma (including patients with lymphoma and CV associated), 2. CV without lymphoma, 3. Salivary gland swelling without lymphoma, 4. other pSS patients. Group 4 was assumed as “base outcome”. The following variables were considered: presence/absence of antinuclear antibodies, anti-Ro, anti-La, low C3, low C4, rheumatoid factor, hypergammaglobulinemia, monoclonal component, leucopoenia, and cryoglobulinemia.
Results 661 patients were selected. Group 1 comprised 40/661 (6.1%), group 2 comprised 17/661 (2.6%), group 3 comprised 180/661 (27.2%), and group 4 comprised 424 (64.1%). Anti-La, hypergammaglobulinemia (IgG > 16 g/l), leucopoenia (<3000/mmc), rheumatoid factor, serum monoclonal component, low C3, low C4, and cryoglobulinemia were selected by univariate analyses. Low C4 [relative-risk ratio (RRR) 8.3, 95% CI 3.6-19.2], anti-La (RRR 5.2, 95% CI 2.3-11.9), cryoglobulins (RRR 6.8, 95% CI 2.1-22.1) and leucopenia (RRR 3.3, 95% CI 1.5-7.05) were the selected variables, by multinomial logistic analyses, that distinguished group 1 from group 4. At least one of the biomarkers selected by univariate analyses was present in all patients with lymphoma, and at least one of the biomarkers selected by multivariate analyses were present in 39/40 patients with lymphoma (97.5%). The majority of variables distinguishing Group 1 from Group 4 were shared with Group 2, while rheumatoid factor and hypergammaglobulinemia were shared with Group 3.
Conclusions Serological biomarkers which raise the level of suspicion of lymphoma or suggest a close follow-up in pSS patients may be identified and confirmed. Rheumatoid factor and hypergammaglobulinemia may reflect the B-cell hyperactivation in patients with salivary gland swelling, which predisposes to lymphoma in pSS. The absence of all the lymphoma-associated biomarkers in pSS may identify patients at lower risk of lymphoma, when CV or salivary gland swelling are not present.
Disclosure of Interest: None Declared