Systemic sclerosis and silica exposure: a rare association in a large Brazilian cohort

The objective of this study is to describe the characteristics of patients with Erasmus syndrome (ES) in a large SSc Brazilian cohort. Nine hundred and forty-seven SSc patients attended at the Scleroderma Outpatient Clinic at two academic medical centers in Brazil and classified as SSc according to the ACR/EULAR criteria were retrospectively studied. Information on demographics, clinical, and laboratory features was obtained by chart review. ES patients had their HLA class II characterized by PCR-SSO method as available. Among the 947 SSc patients studied, nine (0.9 %) had ES. These ES patients were predominantly male (78 %) and smokers (68 %) and presented diffuse SSc (67 %). Mean time of occupational exposure to silica was 13.7 years, with mean age at onset of 47 years. Previous history of tuberculosis was referred by 33 % of the ES patients. All the ES patients presented Raynaud's phenomenon, esophageal involvement, and interstitial lung disease (ILD). Antinuclear antibodies were present in all the ES patients, while anti-topoisomerase I was positive in 44 % and no patient had anticentromere antibody. Three different HLA-DQB alleles (0506, 0305, and 0303) were observed. Compared to non-ES cases, patients with ES were associated with male gender (p < 0.001), diffuse SSc (p < 0.05), ILD (p < 0.05), positive anti-topoisomerase I antibodies (p < 0.05), and death (p < 0.05). Multivariate analysis did not confirm that silicosis is an independent risk factor for SSc. To conclude, ES was rare in this large SSc cohort, although associated with a bad prognosis.