A case of proteinase 3-antineutrophil cytoplasmic antibody-positive Sjögren's syndrome complicated with interstitial nephritis

Abstract

A 65-year-old woman who had fever was admitted. Laboratory data showed renal tubular dysfunction, elevated C-reactive protein, soluble interleukin-2 receptor (sIL-2R), and IgG. Her blood showed proteinase 3-antineutrophil cytoplasmic antibody (PR3-ANCA) as well as antinuclear antibody and anti-Ro/SS-A antibody. Salivary gland and renal biopsy showed inflammatory infiltration of lymphocytes. A diagnosis of Sjögren's syndrome (SS) and interstitial nephritis was made. β₂-microglobulin, sIL-2R, IgG, and PR3-ANCA were decreased in response to medium-dose oral prednisolone. Antineutrophil cytoplasmic antibody could be a new marker for extraglandular features of SS. It would be beneficial for SS patients who have positive ANCA to investigate extraglandular lesions such as interstitial nephritis.

Key words:

• Extraglandular lesions
• Interstitial nephritis
• Proteinase 3-antineutrophil cytoplasmic antibody (PR3-ANCA)
• Sjögren's syndrome