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Abstract: TH-PO680

ANCA Vasculitis in a Patient with Significant Silica Exposure

Session Information

Category: Glomerular Diseases

  • 1402 Glomerular Diseases: Clinical, Outcomes, and Trials

Authors

  • Subramanian, Nivetha, Stanford Medicine, Stanford, California, United States
  • Anand, Shuchi, Stanford Medicine, Stanford, California, United States
Introduction

Exposure to free crystalline silica (silicon dioxide) is classically associated with an array of lung diseases. It has also been associated with ANCA vasculitis. Here we describe a case of ANCA vasculitis attributed to silicosis, a diagnosis that occurred through multi-disciplinary involvement.

Case Description

A 37-year-old male with no past medical history presents with one year of cough and hemoptysis. For the past 20 years, he has worked as a granite cutter, installing counter tops; he smokes 2-3 cigarettes per day. He was found to have a creatinine of 2.5 mg/dL (0.8 mg/dL eight months ago). Labs were notable for nephrotic range proteinuria of 5 g/g creatinine and 3+ hemoglobinuria with 13 RBCs/HPF but normal complements and negative rheumatoid factor, HIV, and anti-HCV. He had positive MPO/P-ANCA, dsDNA, and ANA. CT chest without contrast showed numerous nodules. After discussion between nephrology, rheumatology, infectious disease, and pulmonology, he was admitted for expedited kidney biopsy and bronchoscopy. Kidney biopsy revealed glomerulonephritis with 30% active crescents and both IgG and C3 deposition, not entirely typical for lupus or ANCA vasculitis but concerning for drug-induced or infection-associated ANCA. Bronchoscopy showed hemosiderin laden-macrophages but BAL was inconsistent with diffuse alveolar hemorrhage and negative for tuberculosis through AFB stain and culture. Since his quantiferon was positive and he had immigrated from a TB-endemic region, concern for miliary tuberculosis was high, so he underwent VATS lung biopsy which was consistent with silicosis based on pathology demonstrating nodular aggregates of dust-laden macrophages, fibrosis, and birefringent particles. A diagnosis of ANCA vasculitis associated with silicosis was made. He received rituximab but experienced a severe infusion reaction so treatment was changed to cyclophosphamide and high-dose steroids with improvement in his creatinine although without return to baseline. He is also receiving treatment for latent tuberculosis.

Discussion

Silica exposure has been described in the literature to cause a variety of autoimmune conditions including ANCA vasculitis and lupus although the mechanism is unclear. Our patient’s occupational exposure and biopsies support this diagnosis. This case highlights the importance of a thorough exposure history and multi-disciplinary engagement to arrive at a diagnosis.