Refractory Pleuritis in a Patient with Silicosis, Systemic Sclerosis, and Sjögren’s Syndrome: Considering the Potential Role of Adjuvant-Induced Autoimmunity

BACKGROUND Silicosis, which is caused by the inhalation of crystalline silica, is known to be associated with a variety of autoimmune diseases. Recently, a new pathogenesis called autoimmune/inflammatory syndrome induced by adjuvants (ASIA) has been reported, which occurs after exposure to substances with adjuvant activity, including silica, and shares clinical features observed in several autoimmune diseases. CASE REPORT A 65-year-old man with silicosis was admitted to our hospital due to fever and chronic fatigue. Symptoms such as sicca and Raynaud's phenomenon and pleural effusion appeared as new findings on admission. Examination led to a diagnosis of systemic scleroderma (SSc) and Sjögren's syndrome (SjS). Considering that SjS was the main cause of the disease, corticosteroid therapy was initiated. However, the patient's general condition deteriorated, leading finally to his death. Silica acts as an adjuvant, inducing chronic inflammatory cytokine release. Thus, prolonged exposure to silica can contribute to the development of autoimmune diseases such as SSc and SjS. In this case, the refractory pleuritis may have been related to the pathogenesis of ASIA. ASIA is difficult to manage if the causative adjuvant cannot be eliminated. CONCLUSIONS We described a case of newly diagnosed SSc and SjS with therapy-resistant pleuritis in a patient with silicosis. Silicosis complicated with corticosteroid-resistant autoimmune disease suggests that ASIA, an adjuvant disease, is involved in the pathogenesis. Therefore, not only SSc and SjS but also the pathogenesis of ASIA should be considered in such cases. Since adjuvant exposure is a causative factor in ASIA, avoiding such exposure is crucial.