Bronchiolitis Obliterans Organizing Pneumonia

A 79 year-old male with bronchiolitis obliterans organizing pneumonia (BOOP) is reported herein. The patient presented mild dyspnea and poor appetite with a 4 kg body weight loss for 3 months following a flu-like illness. The chest radiology unveiled bilateral patchy infiltrates with areas of consolidation and ground glass opacities. The pulmonary function test revealed mild restriction and no obstruction. The pathology of open lung biopsy showed interstitial pneumonia with loose myxoedematous tissue in branching plugs within the alveolar ducts and alveoli as well as in intraluminal polypoid nodules within the bronchioles. The patient responded dramatically to the steroid therapy with a nearly complete resolution within a week. Immunohistochemical studies showed rich capillarization with numerous CD34-positive and factor Ⅷ-positive endothelial cells as well as the presence of large S100-posive dendritic cells in the proliferative connective tissue with actin-positive myofibroblasts, comparable with the reported results of the different proliferative connective tissue in BOOP and usual interstitial pneumonia.