Molecular B-cell clonality assay in minor salivary glands as a useful tool for the lymphoma risk assessment in Sjögren's syndrome

OBJECTIVES

Non-Hodgkin's lymphoma (NHL) risk assessment is crucial in Sjögren's syndrome (SS). We studied the prevalence of clonal immunoglobulin gene rearrangements in minor salivary glands (MSG) and their correlations with lymphoma occurrence and with previously established NHL predictors.

METHODS

Molecular B-cell expansion was studied in fresh-frozen MSG of 207 patients with either suspected SS or with suspected lymphoma during SS, using a standardised multiplex PCR assay combined with heteroduplex analysis by microcapillary electrophoresis. The assignation of clonal cases was based on EuroClonality consortium guidelines.

RESULTS

Among 207 studied patients, 31 (15%) had MSG monoclonal B-cell infiltration. Monoclonality was significantly more frequent in patients with SS (28/123, 22.8%) compared with patients without SS (3/84, 3.6%, P<0.001). Monoclonal B-cell infiltration in MSG of SS patients correlated significantly with ongoing salivary gland NHL, salivary gland swelling, CD4+ T-cell lymphopenia, rheumatoid factor (RF) activity, low complement levels and type 2 mixed cryoglobulinemia. The accumulation of biological risk factors was associated with a higher rate of MSG B-cell monoclonality given that patients with only positive RF had no probability of MSG B-cell monoclonality, RF-positive patients with 1 or 2 other risk factors had a 25.0% and 85.7% probability of MSG B-cell monoclonality, respectively.

CONCLUSION

The detection of MSG monoclonal B-cell expansion by this easy-to-perform molecular assay is useful, both at the time of diagnosis and during the course of SS. Monoclonal B-cell expansion is associated with a subset of SS patients presenting either ongoing lymphoma or other established lymphoma predictive factors.

Expert Perspective: Challenges in Sjögren's Disease

The management of Sjögren's disease is challenging because of several factors. Indeed, the clinical presentations are heterogeneous, and one must be able to identify prognostic markers to adapt the follow-up. In addition, there is no validated treatment. Nevertheless, international experts have been working for several years to establish recommendations to guide management. Since research in this field is extremely active, we anticipate the development of effective treatments for our patients in the near future.

Diagnostic utility of a second minor salivary gland biopsy in patients with suspected Sjögren's syndrome: A retrospective cohort study

OBJECTIVE

To determine whether repeated minor salivary gland biopsy (MSGB) has a clinical diagnostic utility in patients with suspicion of Sjögren's syndrome (SS).

METHODS

Clinical, biological, pathological data and physician's diagnosis after each MSGB from patients with suspected primary or secondary SS who had benefited from 2 MSGB at Brest University Hospital between January 1st, 1990 and January 14th, 2015, were retrospectively collected. We compared the characteristics of patients with and without first positive MSGB, concordance between the MSGB, and analyzed the modifications of diagnosis after the second MSGB.

RESULTS

Ninety-three patients were included, first MSGB was positive for 23 and negative for 70. Patients with first positive MSGB had more often renal involvement (P<0.05) and hypergammaglobulinemia (P=0.01), anti-SSA antibodies (P<0.05) and positive second biopsy with focus score ≥ 1 or Chisholm>2 (P<0.01). The mean time between the 2 MSGB was 5.7±4.3 years. The concordance between the results of the 2 biopsies was low (κ = 0.34). MSGB influenced diagnostic's change in 10 cases where the second MSGB was always guided by new specific clinical manifestations.

CONCLUSION

We observed a low concordance between 2 MSGB in patients with suspected pSS in our study. Despite this variability, performing a second MSGB changed the initial diagnosis in only a minority of the patients and was particularly useful when clinical manifestations had deeply evolved.