Primary Sjögren's syndrome in patients with multiple sclerosis

The relationship between multiple sclerosis (MS) and primary Sjögren's syndrome (PSS) is ambiguous; it was suggested that some patients diagnosed with MS may instead have PSS. In a recent epidemiologic study, the prevalence of PSS was 2.7% in southern Sweden. We randomly selected 30 patients with definite MS from our patient population and investigated them for evidence of PSS according to the Copenhagen criteria. One patient had clinical symptoms compatible with PSS and also fulfilled the Copenhagen criteria. In addition, five patients had keratoconjunctivitis sicca, one had xerostomia, and three had histopathologic evidence of sialadenitis in the lower lip salivary glands. However, one of these findings alone is not sufficient to support the diagnosis of PSS. We conclude that MS and PSS may coexist in the same individual, but PSS is not more common among MS patients than expected in the general population.