Chest CT and laboratory test characteristics of microscopic polyangitis with pulmonary infection

Abstract

Objective To investigate the imaging features of chest CT and characteristics of laboratory tests in microscopic polyangitis (MPA) with pulmonary infection. Methods Based on the results of sputum culture, 42 patients with MPA were divided into two groups, MPA with pulmonary infection (16 cases) and MPA without pulmonary infection (26 cases). The results of chest CT images and laboratory tests were compared between the 2 groups by χ2 test (or Fisher exact test) and student t test (or Mann-Whitney U test), respectively. Results Compared with patients without pulmonary infection, patients with pulmonary infection showed patchy opacities (15/16 cases versus 14/26 cases, χ2=5.631, P= 0.018) and consolidations (7/16 cases versus 2/26 cases, χ2=5.657, P= 0.017) more frequently. Patchy opacities showed peripheral distribution less frequently in the MPA with pulmonary infection group than in the MPA without pulmonary infection group (6/15cases versus 12/14 cases, P=0.021). Patients with pulmonary infection showed the same frequent as the patients without pulmonary infection in the following CT findings including ground glass opacities, pleural effusions, mediastinal adenopathy and pulmonary fibrosis (P>0.05). The MPA with pulmonary infection group had higher neutrophil ratio than the MPA without pulmonary infection group (0.84±0.12 versus 0.74±0.11, t= 2.845, P= 0.007). Conclusions The MPA patients with pulmonary infection show patchy opacities and consolidations more frequently, and have higher neutrophil ratio than the MPA without pulmonary infection. The characteristics can be helpful in the diagnosis of pulmonary infection in the MPA patients and guild the treatment. Key words: Microscopic polyangitis; Pneumonia; Tomography, X-ray computed