Should nasal biopsy inevitably be performed for classifying granulomatosis with polyangiitis in patients with rhinosinusitis? A retrospective chart review study

Nasal biopsy is the essential method for differentiating and diagnosing granulomatosis with polyangiitis (GPA) in patients with chronic rhinosinusitis. Nevertheless, in the real clinical settings, there are several cases unable for nasal biopsy. Hence, in this study, we investigated initial clinical manifestations and laboratory factors which could be helpful for diagnosing GPA in cases unable for nasal biopsy performance. We retrospectively reviewed the medical records of 45 patients with GPA. Twenty-five patients exhibited chronic rhinosinusitis, among which 16 patients underwent nasal biopsy. We applied the 2007 European Medicines Agency algorithm for the classification of GPA, the 2012 Chapel Hill Consensus Conferences Nomenclature of Vasculitis and the 2017 American College of Rheumatology/European League Against Rheumatism provisional classification criteria for GPA to them for reclassifying GPA. Among six patients without granuloma on nasal biopsy, three patients with only antineutrophil cytoplasmic antibody (ANCA) and chronic rhinosinusitis could be classified as GPA due to proteinase 3 (PR3)-ANCA (or cytoplasmic (C)-ANCA) positivity. Among nine patients without nasal biopsy, three patients with only chronic rhinosinusitis could be classified as GPA due to GPA-specific lung lesions. When we excluded an item of granuloma in ten GPA patients with granuloma on nasal biopsy, four patients without ANCAs could be classified as GPA due to GPA-specific lung lesions and cartilaginous involvement. In conclusion, PR3-ANCA (or C-ANCA) positivity, GPA-specific lung lesions and cartilaginous involvement could help physicians in charge make a final diagnosis of GPA in cases unable for nasal biopsy.