Association of HRCT Findings Suggestive of Bronchiolitis Obliterans with Bronchial Hyperresponsiveness after Mycoplasma pneumoniae Pneumonia

Yoo, Young; Suh, Dong In; Kim, Do Kyun; Yu, Jinho; Koh, Young Yull; Kim, Chang Keun

Abstract

PURPOSE
Bronchiolitis obliterans (BO) is an uncommon disease of the respiratory bronchioles and alveolar ducts that results in fibrosis and obliteration of the small airways. The causes of BO are diverse, but postinfectious BO is usually seen in children, especially after viral or Mycoplasma pneumoniae (M. pneumoniae) pneumonia. The aim of this study was to evaluate functional abnormalities such as bronchial hyperresponsiveness in the patients with High Resolution Computed Tomography (HRCT) findings suggestive of BO after M. pneumoniae pneumonia. METHODS: The diagnosis of M. pneumoniae pneumonia was made by a fourfold or higher rise in the antibody titers between acute and convalescent phase or a single very high titers (> or =1: 640) among children with clinical pneumonia. HRCT was checked in those with intermittent or chronic respiratory symptoms between one and two years after M. pneumoniae pneumonia. Eighteen patients with HRCT findings suggestive of BO (Group 1) and 24 patients with normal HRCT findings (Group 2) underwent methacholine bronchial challenge and skin prick testing. RESULTS: Mean FEV1 (% predicted) value of Group 1 (92.0%) was significantly lower than that of the Group 2. (101.1%) (P=0.048) The geometric mean of methacholine PC20 in Group 1 (8.5 mg/ mL) was significantly lower than that of the Group 2, (25.7 mg/mL) (P=0.008) with a higher frequency of bronchial hyperresponsiveness (PC20< 8 mg/mL) in Group 1 (38.8%) than in Group 2. (8.3%) (P=0.017) Prevalence of atopy was not different between Group 1 and Group 2, and mean FEV1 (% predicted) value and methacholine PC20 showed no significant difference according to the presence of atopy in either group. CONCLUSION: HRCT findings suggestive of BO after M. pneumoniae pneumonia were associated with functional abnormalities such as lower spirometric values and enhanced bronchial hyperresponsiveness.