Anemia Combined Significantly Increased High-Sensitivity C Reactive Protein and Lung Lesions Lead to the Diagnosis of Granulomatosis with Polyangiitis Proven by Lung Biopsy and Anti-neutrophil Cytoplasmic Antibody Test

Background: To report an atypical case misdiagnosed as lung abscess over the past 2 months, but persistent anemia combined with significantly increased hs-CRP and lung lesions indicated systemic lesion, which led to the diagnosis of granulomatosis with polyangiitis proven by lung biopsy and anti-neutrophil cytoplasmic antibody test (ANCA). Methods: The complete blood count, hs-CRP, and anti-neutrophil cytoplasmic antibody (ANCA) test were performed. The pathology consultation for the lung biopsy was arranged. Results: Hemoglobin was 8.5 g/L, hs-CRP was > 200 mg/L, c-ANCA directed against anti-proteinase 3 (PR3) was positive, pathology consultation reported granulomatous inflammation. Conclusions: When patients have multiple organ dysfunction combined with anemia and significantly increased hs-CRP, physicians should pay attention to systemic vasculitis.