Myeloperoxidase anti-neutrophil cytoplasmic antibody-associated vasculitis with silicosis, alveolar hemorrhage, and rapidly progressive glomerulonephritis: a case report

Abstract

Background: The underlying pathophysiology of some occupational diseases such as silicosis involves autoantibodies. An autoantibody, antineutrophil cytoplasmic antibody (ANCA), has been recently reported and is known to be elevated in diseases such as vasculitis; therefore, the disease is currently known as ANCA-associated vasculitis. The risk of ANCA-associated vasculitis is known to be 25 times higher in patients with silicosis than in those without any occupational disease. In this report, the author describes the case of a man who developed ANCA-associated vasculitis after silicosis, leading to severe alveolar hemorrhage and renal dysfunction.

Case description: A Japanese man in his 50s who was engaged in tunnel construction for 33 years presented with the chief complaint of cough with sputum. Based on chest images and his occupational history, a diagnosis of silicosis was made. In November 2008, urinary occult blood was detected; therefore, myeloperoxidase anti-neutrophil cytoplasmic antibody (MPO-ANCA) levels were measured (15.9 U/mL). In September 2009, he experienced systemic fatigue, fever, night sweats, bloody sputum, and difficulty breathing. Chest images showed new shadows, and MPO-ANCA levels had increased to 690 U/mL. His bronchoalveolar lavage fluid was bloody, confirming alveolar hemorrhage. The bloody sputum resolved spontaneously; however, a subsequent short-term increase in serum creatinine levels was observed. Renal biopsy confirmed necrotizing crescentic glomerulonephritis. Therefore, he was diagnosed with MPO-ANCA-associated vasculitis with silicosis, alveolar hemorrhage, and rapidly progressive glomerulonephritis. Treatment with combination therapy of pulse methylprednisolone sodium succinate and cyclophosphamide led to remission.

Conclusions: For patients with silicosis, accompanied by bloody sputum or other symptoms, ANCA-associated vasculitis, besides tuberculosis and lung cancer, should be considered. It is also necessary to pay close attention to the possible onset of rapidly progressive glomerulonephritis because it is sometimes fatal. In addition, when examining a patient with rapidly progressive glomerulonephritis, attention must be paid to whether the patient has had previous exposure to silica dust, regardless of whether or not the exposure was occupational.

Keywords: Silicosis; alveolar hemorrhage; antineutrophil cytoplasmic antibody-associated vasculitis (ANCA-associated vasculitis); case report; rapidly progressive glomerulonephritis.

Figure 1

Chest images captured in 1999. (A) X-ray image of the plain chest. (B,C) Non-contrast-enhanced computed tomography images of the plain chest showing striations in the lungs and mediastinum in the upper thoracic region. Mediastinal lymphadenopathy with mild calcification is observed.

Figure 2

Chest radiograph captured in November 2008.

Figure 3

Chest images captured in September 2009. (A) X-ray image of the plain chest. (B) Non-contrast-enhanced computed tomography image of the plain chest showing striations in the lungs.

Figure 4

Progression of silicosis from 1999 to 2009. OB, occult blood in urine; Prot., urine protein.

Figure 5

Bronchoalveolar lavage fluid collected in September 2009. The recovered bronchoalveolar lavage fluid is shown in order from left to right. The redness of the recovered fluid continuously increased.

Figure 6

Histopathology of renal tissue using hematoxylin and eosin staining. The image shows half-moon-shaped cellular formations in the glomerulus at 40× magnification.

Figure 7

Histopathology of renal tissue using Periodic acid-Schiff staining. (A) Magnification: 10×; (B) magnification: 40×.