Background: Pemphigus is an autoimmune bullous disease characterized by the presence of antidesmoglein autoantibodies. However, the mechanism of its autoantibody production remains unknown. In previous reports, we have described rare cases of pemphigus and pemphigoid associated with silicosis. It is well known that during long-term silicosis, some autoimmune diseases, such as systemic sclerosis, systemic lupus erythematosus or rheumatoid arthritis, can occur. Objective: The aim of this study was to explore the presence of pemphigus or pemphigoid autoantibodies in silicosis patients without clinical bullous diseases or collagen diseases. Method: The presence of pemphigus antibodies was examined in 54 silicosis patients with no associated bullous diseases, using immunofluorescence, the enzyme-linked immunosorbent assay (ELISA) for desmoglein 1 and 3, and immunoblotting methods. In the antibody-positive cases, HLA genotyping of peripheral lymphocytes was performed with PCR-RFLP. Results: Seven out of the 54 patients were found to be positive for pemphigus antibodies and 1 for bullous pemphigoid by immunofluorescence. In addition, by ELISA, 6 patients were found to be positive against the desmoglein 1 antigen, 2 against the desmoglein 3 antigen and 2 against both desmoglein 1 and desmoglein 3. Conclusion: The results of the present study strongly suggest the occurrence of pemphigus and pemphigoid autoantibodies in patients with silicosis. It remains unclear whether such patients will develop an autoimmune bullous disease in the future. Accordingly, long-term follow-up of antibody-positive patients is required.

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Pemphigus vulgaris has never before been associated with silicosis, although there are many reports of silicosis accompanied by several autoimmune diseases such as progressive systemic sclerosis, systemic lupus erythematosus, dermatomyositis or rheumatoid arthritis. We observed a patient with pemphigus vulgaris accompanied with silicosis. The patient was a 75-year-old man with a 2-month history of repeated oral erosions and blisters on the back, thighs and axillas. Histological examination showed suprabasal cleavage with acantholysis. Immunoblotting analysis demonstrated binding of the patient’s serum to the 130-kD pemphigus vulgaris antigen (desmoglein 3) and the 160-kD pemphigus foliaceus antigen (desmoglein 1). The patient has radiographically been diagnosed as having silicosis. An elevated serum IgG, antinuclear antibody, anti-ssDNA, antimicrosomal antibodies and a biologically false-positive reaction to the Wassermann test were also detected. Although the clinical symptoms improved after treatment with systemic steroids, the patient died due to pneumonia. This is the first reported case in which the characteristics of both pemphigus vulgaris and silicosis could be detected.

Bullous pemphigoid (BP) has never before been reported to associate with silicosis, although there are numerous reports of silicosis accompanied by different autoimmune diseases, such as systemic sclerosis, systemic lupus erythematosus, dermatomyositis or rheumatoid arthritis. We report on a 63-year-old Japanese patient with silicosis who developed tensed bullae, erosions and macular pigmentation on the trunk and extremities. Indirect immunofluorescence revealed anti-basement-membrane-zone antibodies; immunoblotting analysis demonstrated that the patient’s serum reacted with the 230-kD BP antigen in the epidermal extracts, as well as a recombinant protein of the NC16a domain of 180-kD BP antigen. Clinical symptoms improved after treatment with systemic steroids. To the best of our knowledge, this is the first reported case of BP associated with silicosis.