Stonemason's systemic vasculitis: three cases and a dilemma

Environmental factors influencing the risk of ANCA-associated vasculitis

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a group of diseases characterized by inflammation and destruction of small and medium-sized blood vessels. Clinical disease phenotypes include microscopic polyangiitis (MPA), granulomatosis with polyangiitis (GPA), and eosinophilic granulomatosis with polyangiitis (EGPA). The incidence of AAV has been on the rise in recent years with advances in ANCA testing. The etiology and pathogenesis of AAV are multifactorial and influenced by both genetic and environmental factors, as well as innate and adaptive immune system responses. Multiple case reports have shown that sustained exposure to silica in an occupational environment resulted in a significantly increased risk of ANCA positivity. A meta-analysis involving six case-control studies showed that silica exposure was positively associated with AAV incidence. Additionally, exposure to air pollutants, such as carbon monoxide (CO), is a risk factor for AAV. AAV has seasonal trends. Studies have shown that various environmental factors stimulate the body to activate neutrophils and expose their own antigens, resulting in the release of proteases and neutrophil extracellular traps, which damage vascular endothelial cells. Additionally, the activation of complement replacement pathways may exacerbate vascular inflammation. However, the role of environmental factors in the etiology of AAV remains unclear and has received little attention. In this review, we summarized the recent literature on the study of environmental factors, such as seasons, air pollution, latitude, silica, and microbial infection, in AAV with the aim of exploring the relationship between environmental factors and AAV and possible mechanisms of action to provide a scientific basis for the prevention and treatment of AAV.

ANCA vasculitis and IgA nephropathy linked to silica exposure

There is a recognized association between silica exposure and Antineutrophil cytoplasmic antibodies (ANCA)-associated vasculitis (AAV); however, no clear association between silica exposure and Immunoglobulin A (IgA) nephropathy. We describe the case of a 26-year-old male stonemason who presents with hilar lymphadenopathy, haematuria and acute kidney injury related to silica exposure, AAV and IgA nephropathy. He was asymptomatic on presentation; urinalysis revealed glomerular haematuria (>1000 red blood cells/L) and proteinuria (protein-to-creatinine ratio 84 mg/mmol). ANCA anti-myeloperoxidase serology was strongly positive. Mediastinal lymph node biopsy revealed multiple necrotizing granulomas with silica inclusions, and renal biopsy demonstrated crescentic glomerulonephritis and mesangial IgA staining. The patient was treated with cyclophosphamide and high-dose prednisolone with subsequent improvement in renal function. To our knowledge, this is the first report of both ANCA vasculitis and IgA nephropathy in the setting of silica exposure. This case highlights the relevance of occupational exposures in renal disease, and the immune-stimulatory effect of silica.