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We read with great interest the new ultrasound scoring system of salivary glands for primary Sjogren’s syndrome (pSS) developed by Outcome Measures in Rheumatology (OMERACT) and recently reported by Jousse-Joulin et al .1 The salivary gland ultrasound (SGUS) is a simple, non-irradiating, non-expensive and accessible assessment tool. Several previous SGUS scoring systems have been proposed so far, but not all of them take into account every pathological features, especially in the parotid gland (such as hyperechoic bands) for the diagnosis of pSS. The lack of consensus between each of these SGUS scoring systems also had a negative impact on the reproducibility of the examination so far. By offering an updated consensual classification, the OMERACT initiative therefore constitutes an undeniable progress for the diagnosis of pSS.
Recently, in a multicentre prospective study of 97 patients referred for clinical sicca syndrome (39 pSS and 22 secondary Sjogren’s syndrome (sSS) according to American-European Consensus Group (AECG) criteria in comparison with 36 controls), we reported good performances of various SGUS scoring systems for the diagnosis of pSS or sSS (area under the curve between 0.885–0.915 (pSS) and 0.808–0.851 (sSS) according to the used ultrasound scores, respectively).2 After the diagnosis of SS, patients are considered at high risk of B lymphoma, a classical and severe complication of SS. The progressive continuum of glandular B lymphocyte hyperactivity, initially polyclonal and then oligoclonal, with the presence of abnormal germinative centres, production of rheumatoid factor, deposition of immune complexes characterised by the consumption of the complement and the presence of cryoglobulinemic vasculitis which may subsequently lead to monoclonal B lymphocyte expansion and low-grade marginal area B lymphoma, is now well accepted and requires specific monitoring of patients with pSS.3
In this correspondence, we would like to draw attention on the association between SGUS characteristics and systemic complications of pSS, with a focus on cryoglobulinemic vasculitis (a well-known risk factor for progression to B lymphoma) and lymphoma itself. The characteristics of our population are shown in table 1.3 There were three B lymphomas in our population, all found in the pSS group (prevalence of 7.7% in the pSS group). Cryoglobulinemic vasculitis was present in 3 (7.7%), 2 (9.0%) and 1 (2.8%) of the pSS, sSS and control group, respectively. Factors associated with lymphomas were severe salivary dryness defined by an unstimulated salivary flow <0.5 g/5 min and pathological SGUS (regardless of the classification used) (observed in all patients with lymphoma, p<0.01). Pathological SGUS was also associated with the presence of cryoglobulinemic vasculitis (OR=44.0 (3.26–583), p<0.001). No lymphoma or cryoglobulinemic vasculitis was found in patients with normal SGUS. In all patient with lymphoma or cryoglobulinemic vasculitis, the salivary glands were all extremely pathological in ultrasound and characterised by a heterogeneous parenchyma containing either numerous cystic lesions with no healthy parenchyma left or significant fibrosis attested by the presence of numerous hyperechoic bands. All these cases fulfilled the definition of a stage 3 of the new OMERACT classification.1
These results confirm the data reported by Thender et al 4 on the association between morphological SGUS damages (particularly of the parotid glands), usual associated-risk factors for progression to lymphoma (CD4 lymphopenia, cryoglobulinemic vasculitis, germinative centre on accessory salivary gland biopsy) and the existence or occurrence of lymphoma. Nevertheless, our cross-sectional data do not allow to conclude on the prognostic value of SGUS for lymphoma occurrence in pSS. These results nonetheless support the use of this tool in daily practice and its systematic inclusion in the assessment of prospective cohorts of pSS, which would allow the evaluation of the relevance of SGUS features as predictive markers for lymphoma. In the end, the prospective evaluation of SGUS results will help to precise the place of SGUS examination in the global follow-up and management of patients with pSS, beyond diagnosis.
All authors would like to thank the patients who participated in this study.
Contributors GC included patients, conducted inclusion visits, performed ultrasound examinations, analysed results and statistics and wrote the manuscript. AM included patients, conducted inclusion visits, analysed results and statistics and wrote the manuscript. J-DA and AL analysed results and statistics and wrote the manuscript. AB performed ultrasound examinations, analysed results and wrote the manuscript. AP, MDB and FM included patients, analysed results and wrote the manuscript.
Competing interests None declared.
Patient consent for publication Not required.
Ethics approval All patients were informed of the objectives and procedure of the study and gave their consent. The study was approved by the ethics committee of Rennes university hospital (Avis n°16.75, May 2016).
Provenance and peer review Not commissioned; internally peer reviewed.
Data availability statement The cohort database is supervised by GC and AM. Data are available upon reasonable request. All data relevant to the study are included in the article.
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