Exposure to silica and primary Sjögren’s syndrome in a dental technician

L. Astudillo, L. Sailler, M. Ecoiffier, J. Giron1, B. Couret and E. Arlet-Suau

Department of Internal Medicine and 1Department of Radiology, University School of Medicine Purpan, Toulouse, France

Correspondence to: L. Astudillo, Department of Internal Medicine, University School of Medicine Purpan, CHU Purpan Unité J. Tapie, 1 place du Docteur Baylac, 31059 Toulouse Cedex, France. E-mail: astudillo.l{at}chu-toulouse.fr

SIR, We report a rare case of primary Sjögren’s syndrome in a retired dental technician exposed to silica.

A 72-yr-old man was admitted to hospital because of weight loss of 4 kg that had developed over 3 months, and fatigue. He complained of oral and ocular dryness, arthralgia of the knees with morning stiffness, severe dry cough and Raynaud’s phenomenon. On physical examination, fine crackles were found in both lungs. Schirmer’s test was positive and Rose Bengal staining showed keratoconjunctivitis sicca. Biological assessment revealed an erythrocyte sedimentation rate of 48 mm at 1 h, C-reactive protein 30 mg/l and fibrinogen 4.3 g/l. Protein electrophoresis revealed hypergammaglobulinaemia of 20 g/l. Full blood count, hepatic enzymes and lactate dehydrogenase were normal. Antinuclear antibodies were positive at 1/1256 with anti-SSA. Double-stranded anti-DNA, anti-RNP, anti-Sm, anti-Jo1, anti-PM-Scl and anti-Scl 70 antibodies were negative. The Waaler–Rose reaction and complement testing were negative. A chest X-ray showed a moderate bilateral interstitial pattern, and high-resolution chest CT scan revealed diffuse lobular septal thickening, bronchial distortion, micronodules in the upper lobes and some mediastinal lymph nodes. This aspect was consistent with pneumoconiosis or Sjögren’s disease. Pulmonary function testing revealed a moderate restrictive syndrome with a decrease of 30% in transfer factor in the lungs. Lip biopsy showed a lymphocytic infiltrate (grade III of Chisholm). Capillaroscopy showed dystrophic large capillaries without megacapillaries. Bronchoalveolar lavage showed lymphocytic alveolitis and silicotic fragments and moderate anthracosis.

A diagnosis of primary Sjögren’s syndrome associated with silica exposure was based on the Vitali diagnostic criteria [1] and the exposure, the delay and the presence of silicotic fragments in bronchoalveolar lavage. The patient had worked as a dental technician for 46 yr (from age 14 to 60 yr), and a chest X-ray and pulmonary function tests 12 yr previously were normal. His general condition improved during 2 months of treatment with hydroxychloroquine (400 mg daily).

The relationship between silica exposure and the development of systemic diseases, such as rheumatoid arthritis and systemic sclerosis, has been well known since the first descriptions by Caplan [2] and Erasmus [3]. A high frequency of antinuclear antibodies and rheumatoid factors was reported in coal-miners [4]. A high prevalence of antinuclear antibodies was also found in silica-exposed subjects [4]. Systemic lupus erythematosus has also been reported in silica-exposed patients [5].

The association between primary Sjögren’s syndrome and exposure to silica has been reported in only six cases in the literature—in coal-miners and in workers from a factory producing scouring powder. In a study of 50 workers exposed to silica in a factory making scouring powder over a period of about 6 yr, Sanchez-Roman et al. [4] found that 64% of workers (32/50) presented with autoimmune processes (three with primary and three with secondary Sjögren’s syndrome, five with systemic sclerosis, three with systemic lupus erythematosus, five with overlap syndrome and 13 with undefined collagen diseases). Moreover, antinuclear antibodies was found in 72% of the workers (36/50). Puisieux et al. [6] reported three cases of primary Sjögren’s syndrome in silicotic coal miners in the French literature. In these cases, primary Sjögren’s syndrome occurred when the patients were about 60 yr old and were already indemnified for silicosis. Orriols et al. [7] reported a case of sicca syndrome and silicoproteinosis in a dental technician and found high peaks of silicon and aluminium in lung and salivary gland by scanning electron microscopy and energy-dispersive X-ray analysis. The authors suggested that, in their case, sicca syndrome had been caused by inorganic deposition.

Our case seems to be related to an autoimmune process, because of the presence of a high titre of antinuclear antibodies with anti-SSA (Ro).

However, a fortuitous association of primary Sjögren’s syndrome with exposure to silica cannot be excluded. More observations such as those described here need to be reported (i) in order to improve our knowledge of the spectrum of autoimmune manifestations that can complicate occupational exposure to silica, and (ii) because such an association may have medicolegal relevance.

References

  1. Vitali C, Bombardieri S, Moutsopoulos HM et al. Assessment of the European classification criteria for Sjögren’s syndrome in a series of clinically defined cases: results of a prospective multicenter study. Ann Rheum Dis 1996;55:116–21[Abstract]
  2. Caplan A. Certain radiological appearances in the chest of coal-miners suffering from rheumatoid arthritis. Thorax 1953; 8:29–37[ISI]
  3. Erasmus LD. Scleroderma in gold-miners on the Witwatersrand and the particular reference to pulmonary manifestations. S Afr J Lab Clin Med 1957;3:209–31
  4. Sanchez-Roman J, Wichmann I, Salaberri J, Varela JM, Nuñez-Roldan A. Multiple clinical and biological autoimmune manifestations in 50 workers after occupational exposure to silica. Ann Rheum Dis 1993;52:534–8[Abstract]
  5. Rosenman KD, Moore-Fuller M, Reilly MJ. Connective tissue disease and silicosis. Am J Ind Med 1999;35:375–81[CrossRef][ISI][Medline]
  6. Puisieux F, Hachulla E, Brouillard M, Hatron PY, Devulder B. Silicosis and primary Gougerot–Sjogren syndrome. Rev Med Intern 1994;15:575–9[ISI]
  7. Orriols R, Ferrer J, Tura JM, Xaus C, Coloma R. Sicca syndrome and silicoproteinosis in a dental technician. Eur Respir J 1997; 10:731–4[Abstract/Free Full Text]
Accepted 27 February 2003





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